<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2021 Workiva-->
<!--r:c8d3b8b3-a6e3-4272-b711-b4240a17d320,g:89170b0c-9bb6-415d-aed5-b6b6381c003c-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.boozallen.com/role/ConsolidatedStatementsofStockholdersEquity" xlink:type="simple" xlink:href="bah-20210331.xsd#ConsolidatedStatementsofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/ConsolidatedStatementsofStockholdersEquity" xlink:type="extended" id="i2c418828b13547ffbb57aef9ca84ab44_ConsolidatedStatementsofStockholdersEquity">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_7603853b-40bf-447b-9553-908559349fcd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_7603853b-40bf-447b-9553-908559349fcd" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_64000b1e-6286-4158-ad6a-6118664e50ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_SharesOutstanding_64000b1e-6286-4158-ad6a-6118664e50ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_c0fe7b3f-4251-4ecf-ad3a-a06c91c1f00f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_StockholdersEquity_c0fe7b3f-4251-4ecf-ad3a-a06c91c1f00f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_426c2a6c-47f3-4305-82d3-4c94db8d8d41" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_426c2a6c-47f3-4305-82d3-4c94db8d8d41" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_896349b7-1865-4bd9-82fa-445275fa999f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_896349b7-1865-4bd9-82fa-445275fa999f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_67edbf83-4310-475d-ab9e-82f220c6c886" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_67edbf83-4310-475d-ab9e-82f220c6c886" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_e2ebcc21-7d32-4ae3-864f-84a98b6b881b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_e2ebcc21-7d32-4ae3-864f-84a98b6b881b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_98b98cb8-2c6a-4721-82f1-ebbf4a6e6324" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_98b98cb8-2c6a-4721-82f1-ebbf4a6e6324" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_0cda8b4f-3e67-4cc6-ba47-1a442f05f968" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_0cda8b4f-3e67-4cc6-ba47-1a442f05f968" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureRestrictedStockUnitsVesting_251bf168-04dd-4c4e-a3a1-b0a0af7e7467" xlink:href="bah-20210331.xsd#bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureRestrictedStockUnitsVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureRestrictedStockUnitsVesting_251bf168-04dd-4c4e-a3a1-b0a0af7e7467" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_31454ef7-2edb-4523-ab0b-e30f3c73d1c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_NetIncomeLoss_31454ef7-2edb-4523-ab0b-e30f3c73d1c3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdateExtensibleList_863cc947-dd12-46a8-8adf-d4871abcd1ec" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountingStandardsUpdateExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_AccountingStandardsUpdateExtensibleList_863cc947-dd12-46a8-8adf-d4871abcd1ec" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0e9e4248-fccf-4a94-a4d8-3fb6a1aa4667" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_0e9e4248-fccf-4a94-a4d8-3fb6a1aa4667" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCash_e8925df7-b271-49c7-9d06-846fb9a2a02a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_DividendsCash_e8925df7-b271-49c7-9d06-846fb9a2a02a" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_11c36c47-6240-445a-aca4-08162d5fbe19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2a905143-0d78-44a3-9cce-ccd53e20bc44" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_11c36c47-6240-445a-aca4-08162d5fbe19" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_b95c3217-40ac-4b4f-ad16-307bb116a87e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5d0b4c03-7f95-4920-b8c1-76531038e0b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_00c8138b-debe-4d89-b11b-2f60c6044358" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_7603853b-40bf-447b-9553-908559349fcd" xlink:to="loc_us-gaap_StatementTable_00c8138b-debe-4d89-b11b-2f60c6044358" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_e020dc90-6777-4266-80ee-33f6d99f6b0b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_00c8138b-debe-4d89-b11b-2f60c6044358" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_e020dc90-6777-4266-80ee-33f6d99f6b0b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_e020dc90-6777-4266-80ee-33f6d99f6b0b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e020dc90-6777-4266-80ee-33f6d99f6b0b" xlink:to="loc_us-gaap_EquityComponentDomain_e020dc90-6777-4266-80ee-33f6d99f6b0b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_e020dc90-6777-4266-80ee-33f6d99f6b0b" xlink:to="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_1491adc4-d942-4120-b825-1d83e92c92d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:to="loc_us-gaap_CommonStockMember_1491adc4-d942-4120-b825-1d83e92c92d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockMember_009c66e6-873d-42ca-b926-b5aa689e930a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:to="loc_us-gaap_TreasuryStockMember_009c66e6-873d-42ca-b926-b5aa689e930a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_191e880f-02b8-4168-8538-86d85b864f22" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_191e880f-02b8-4168-8538-86d85b864f22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_489e88ae-7e5f-442b-b4f0-2d017a2f137b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:to="loc_us-gaap_RetainedEarningsMember_489e88ae-7e5f-442b-b4f0-2d017a2f137b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1364a85a-83ca-4769-a8e3-731a2f373278" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_29c04455-2f8f-47a7-97ee-1e9d7f4f772f" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_1364a85a-83ca-4769-a8e3-731a2f373278" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_5ad3f7ea-fac5-4dc6-b4fa-5e2ade98e0e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_00c8138b-debe-4d89-b11b-2f60c6044358" xlink:to="loc_us-gaap_StatementClassOfStockAxis_5ad3f7ea-fac5-4dc6-b4fa-5e2ade98e0e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_5ad3f7ea-fac5-4dc6-b4fa-5e2ade98e0e5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5ad3f7ea-fac5-4dc6-b4fa-5e2ade98e0e5" xlink:to="loc_us-gaap_ClassOfStockDomain_5ad3f7ea-fac5-4dc6-b4fa-5e2ade98e0e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_dd021270-a8f4-4d26-871c-d75b50f43b42" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_5ad3f7ea-fac5-4dc6-b4fa-5e2ade98e0e5" xlink:to="loc_us-gaap_ClassOfStockDomain_dd021270-a8f4-4d26-871c-d75b50f43b42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_e9bdf824-e331-4995-9a3c-4a83a598a6fa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_dd021270-a8f4-4d26-871c-d75b50f43b42" xlink:to="loc_us-gaap_CommonClassAMember_e9bdf824-e331-4995-9a3c-4a83a598a6fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_3c6339d8-bb8a-497f-9d6c-eed1481a856c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_00c8138b-debe-4d89-b11b-2f60c6044358" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_3c6339d8-bb8a-497f-9d6c-eed1481a856c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_3c6339d8-bb8a-497f-9d6c-eed1481a856c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_3c6339d8-bb8a-497f-9d6c-eed1481a856c" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_3c6339d8-bb8a-497f-9d6c-eed1481a856c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8ab5c380-387f-4283-bdb8-b8df1ea14296" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_3c6339d8-bb8a-497f-9d6c-eed1481a856c" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8ab5c380-387f-4283-bdb8-b8df1ea14296" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_78ca78e0-2e32-4bc5-99ec-7c2c0a22d64d" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_8ab5c380-387f-4283-bdb8-b8df1ea14296" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_78ca78e0-2e32-4bc5-99ec-7c2c0a22d64d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="extended" id="ibfe71671cadb4a3bb041714a53240a72_SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_90e3dd1e-92b2-46c1-aeff-2817f1cb395f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_4aab2a54-a74c-4ec2-9a3e-a631063cc9e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_90e3dd1e-92b2-46c1-aeff-2817f1cb395f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_4aab2a54-a74c-4ec2-9a3e-a631063cc9e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_aacbae24-47b0-4b8f-ba30-54bfc47f5181" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_90e3dd1e-92b2-46c1-aeff-2817f1cb395f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_aacbae24-47b0-4b8f-ba30-54bfc47f5181" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e744c582-3c50-491c-a886-a5351efcd7fa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_aacbae24-47b0-4b8f-ba30-54bfc47f5181" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e744c582-3c50-491c-a886-a5351efcd7fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e744c582-3c50-491c-a886-a5351efcd7fa_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e744c582-3c50-491c-a886-a5351efcd7fa" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e744c582-3c50-491c-a886-a5351efcd7fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9c09fd5-9833-4842-8acf-10fc8bee38a7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e744c582-3c50-491c-a886-a5351efcd7fa" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9c09fd5-9833-4842-8acf-10fc8bee38a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_e07c0339-ff86-485d-b6a3-787b928b9049" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9c09fd5-9833-4842-8acf-10fc8bee38a7" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_e07c0339-ff86-485d-b6a3-787b928b9049" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_5f95fb25-04be-4420-a5bf-6efcec4ae5f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_d9c09fd5-9833-4842-8acf-10fc8bee38a7" xlink:to="loc_us-gaap_ComputerEquipmentMember_5f95fb25-04be-4420-a5bf-6efcec4ae5f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_efcae19b-970f-417d-bda3-a388bab9fe9f" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_aacbae24-47b0-4b8f-ba30-54bfc47f5181" xlink:to="loc_srt_RangeAxis_efcae19b-970f-417d-bda3-a388bab9fe9f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_efcae19b-970f-417d-bda3-a388bab9fe9f_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_efcae19b-970f-417d-bda3-a388bab9fe9f" xlink:to="loc_srt_RangeMember_efcae19b-970f-417d-bda3-a388bab9fe9f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d1d16dda-a2d5-4c5d-b92a-7cfab918b1d6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_efcae19b-970f-417d-bda3-a388bab9fe9f" xlink:to="loc_srt_RangeMember_d1d16dda-a2d5-4c5d-b92a-7cfab918b1d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_1652cf35-3f16-47e5-9d35-5fa2fd36f4df" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d1d16dda-a2d5-4c5d-b92a-7cfab918b1d6" xlink:to="loc_srt_MinimumMember_1652cf35-3f16-47e5-9d35-5fa2fd36f4df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_b7044a39-9e24-48d9-94db-06a4bd9021bc" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d1d16dda-a2d5-4c5d-b92a-7cfab918b1d6" xlink:to="loc_srt_MaximumMember_b7044a39-9e24-48d9-94db-06a4bd9021bc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/SummaryofSignificantAccountingPoliciesIntangibleAssetsandGoodwillDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#SummaryofSignificantAccountingPoliciesIntangibleAssetsandGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SummaryofSignificantAccountingPoliciesIntangibleAssetsandGoodwillDetails" xlink:type="extended" id="i281e4d33219041258e4fa6be4e5bb16c_SummaryofSignificantAccountingPoliciesIntangibleAssetsandGoodwillDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5023f52c-3d6d-424d-902e-24b007f5796e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_f9a35e26-ea24-4f42-8ff1-41068e8b289d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5023f52c-3d6d-424d-902e-24b007f5796e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_f9a35e26-ea24-4f42-8ff1-41068e8b289d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_b525e81c-a89e-4356-baab-068e1ed0a656" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOfIntangibleAssetsFinitelived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5023f52c-3d6d-424d-902e-24b007f5796e" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsFinitelived_b525e81c-a89e-4356-baab-068e1ed0a656" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_b234d460-9d06-468d-8a5c-b16fd17a9be0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5023f52c-3d6d-424d-902e-24b007f5796e" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_b234d460-9d06-468d-8a5c-b16fd17a9be0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_1d56ac58-0197-4313-a81e-353d368b401c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5023f52c-3d6d-424d-902e-24b007f5796e" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_1d56ac58-0197-4313-a81e-353d368b401c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e974ec78-eef5-474c-85b3-571dddfc84b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_5023f52c-3d6d-424d-902e-24b007f5796e" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e974ec78-eef5-474c-85b3-571dddfc84b7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_900eace7-baa8-4cfe-af10-722669be68dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e974ec78-eef5-474c-85b3-571dddfc84b7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_900eace7-baa8-4cfe-af10-722669be68dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_900eace7-baa8-4cfe-af10-722669be68dc_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_900eace7-baa8-4cfe-af10-722669be68dc" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_900eace7-baa8-4cfe-af10-722669be68dc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9af19926-ae59-4f56-b16a-6715da7f7c26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_900eace7-baa8-4cfe-af10-722669be68dc" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9af19926-ae59-4f56-b16a-6715da7f7c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_0cb0911b-d331-4c9b-80d2-6ec7dedba71b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9af19926-ae59-4f56-b16a-6715da7f7c26" xlink:to="loc_us-gaap_CustomerRelationshipsMember_0cb0911b-d331-4c9b-80d2-6ec7dedba71b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_8a9cfee9-941c-447a-8048-ecec78628185" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_9af19926-ae59-4f56-b16a-6715da7f7c26" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_8a9cfee9-941c-447a-8048-ecec78628185" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a6c12087-6213-448f-af75-a5584af7dbab" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_e974ec78-eef5-474c-85b3-571dddfc84b7" xlink:to="loc_srt_RangeAxis_a6c12087-6213-448f-af75-a5584af7dbab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a6c12087-6213-448f-af75-a5584af7dbab_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a6c12087-6213-448f-af75-a5584af7dbab" xlink:to="loc_srt_RangeMember_a6c12087-6213-448f-af75-a5584af7dbab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_4d8753fa-8664-4eb2-b51c-26da75f22e64" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a6c12087-6213-448f-af75-a5584af7dbab" xlink:to="loc_srt_RangeMember_4d8753fa-8664-4eb2-b51c-26da75f22e64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_f635d8d3-bfb4-4f71-ac1f-3e822fc207d5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4d8753fa-8664-4eb2-b51c-26da75f22e64" xlink:to="loc_srt_MinimumMember_f635d8d3-bfb4-4f71-ac1f-3e822fc207d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_4ee4b9db-2f95-4bca-9c98-c861cf2a0759" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_4d8753fa-8664-4eb2-b51c-26da75f22e64" xlink:to="loc_srt_MaximumMember_4ee4b9db-2f95-4bca-9c98-c861cf2a0759" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#RevenueDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="extended" id="i276dfbfa8c014d469fad905573138543_RevenueDisaggregationofRevenueDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_0923d36d-aa5a-477e-aa0f-50b578dcecb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_2ca2ad6a-26dd-4a5f-af91-65c164baf8d9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_0923d36d-aa5a-477e-aa0f-50b578dcecb6" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_2ca2ad6a-26dd-4a5f-af91-65c164baf8d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage_9efcbc68-f100-424a-80f4-df46e81fbdf1" xlink:href="bah-20210331.xsd#bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_0923d36d-aa5a-477e-aa0f-50b578dcecb6" xlink:to="loc_bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage_9efcbc68-f100-424a-80f4-df46e81fbdf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_d4855c47-89f3-429d-b410-539830b30792" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_0923d36d-aa5a-477e-aa0f-50b578dcecb6" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_d4855c47-89f3-429d-b410-539830b30792" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_e1e99f8f-2928-4bfb-8761-9efa51e10b0d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d4855c47-89f3-429d-b410-539830b30792" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_e1e99f8f-2928-4bfb-8761-9efa51e10b0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_e1e99f8f-2928-4bfb-8761-9efa51e10b0d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_e1e99f8f-2928-4bfb-8761-9efa51e10b0d" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_e1e99f8f-2928-4bfb-8761-9efa51e10b0d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_1f46020a-dc92-400d-9d08-efa28d0b5a43" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_e1e99f8f-2928-4bfb-8761-9efa51e10b0d" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_1f46020a-dc92-400d-9d08-efa28d0b5a43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_CostReimbursableContractMember_a47dfbf5-da69-415a-a4a6-515a596aff85" xlink:href="bah-20210331.xsd#bah_CostReimbursableContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_1f46020a-dc92-400d-9d08-efa28d0b5a43" xlink:to="loc_bah_CostReimbursableContractMember_a47dfbf5-da69-415a-a4a6-515a596aff85" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_87b9dd36-5e45-44ae-a9aa-4dc2e1ab6363" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_1f46020a-dc92-400d-9d08-efa28d0b5a43" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_87b9dd36-5e45-44ae-a9aa-4dc2e1ab6363" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember_83d3cf01-7d97-4826-9e95-6d78393d9f32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FixedPriceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_1f46020a-dc92-400d-9d08-efa28d0b5a43" xlink:to="loc_us-gaap_FixedPriceContractMember_83d3cf01-7d97-4826-9e95-6d78393d9f32" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_d1185024-6b0e-42cc-be27-5981702f745b" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d4855c47-89f3-429d-b410-539830b30792" xlink:to="loc_srt_StatementGeographicalAxis_d1185024-6b0e-42cc-be27-5981702f745b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_d1185024-6b0e-42cc-be27-5981702f745b_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_d1185024-6b0e-42cc-be27-5981702f745b" xlink:to="loc_srt_SegmentGeographicalDomain_d1185024-6b0e-42cc-be27-5981702f745b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_46705cae-723e-4c76-8eeb-31645e9f79dc" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_d1185024-6b0e-42cc-be27-5981702f745b" xlink:to="loc_srt_SegmentGeographicalDomain_46705cae-723e-4c76-8eeb-31645e9f79dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_dceed22b-a49d-4b69-97c8-be0669182403" xlink:href="https://xbrl.sec.gov/country/2020/country-2020-01-31.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_46705cae-723e-4c76-8eeb-31645e9f79dc" xlink:to="loc_country_US_dceed22b-a49d-4b69-97c8-be0669182403" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_3b8e26ba-dec6-4b35-b163-18ac9d519dcd" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d4855c47-89f3-429d-b410-539830b30792" xlink:to="loc_srt_MajorCustomersAxis_3b8e26ba-dec6-4b35-b163-18ac9d519dcd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_3b8e26ba-dec6-4b35-b163-18ac9d519dcd_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_3b8e26ba-dec6-4b35-b163-18ac9d519dcd" xlink:to="loc_srt_NameOfMajorCustomerDomain_3b8e26ba-dec6-4b35-b163-18ac9d519dcd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_4a8480fa-0ed1-4e57-a845-993d4c7ed015" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_3b8e26ba-dec6-4b35-b163-18ac9d519dcd" xlink:to="loc_srt_NameOfMajorCustomerDomain_4a8480fa-0ed1-4e57-a845-993d4c7ed015" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DefenseClientsMember_a37b3e61-ffcc-4cca-b2e4-e661df5600d8" xlink:href="bah-20210331.xsd#bah_DefenseClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_4a8480fa-0ed1-4e57-a845-993d4c7ed015" xlink:to="loc_bah_DefenseClientsMember_a37b3e61-ffcc-4cca-b2e4-e661df5600d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_IntelligenceClientsMember_44b871d2-c11c-489d-a9e8-272b62ea63ee" xlink:href="bah-20210331.xsd#bah_IntelligenceClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_4a8480fa-0ed1-4e57-a845-993d4c7ed015" xlink:to="loc_bah_IntelligenceClientsMember_44b871d2-c11c-489d-a9e8-272b62ea63ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_CivilClientsMember_fa48ccb2-b246-442b-a0cf-c37db69ed7b4" xlink:href="bah-20210331.xsd#bah_CivilClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_4a8480fa-0ed1-4e57-a845-993d4c7ed015" xlink:to="loc_bah_CivilClientsMember_fa48ccb2-b246-442b-a0cf-c37db69ed7b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_GlobalCommercialClientsMember_feb462ee-7f17-4091-9ac3-fdbeec3cb7af" xlink:href="bah-20210331.xsd#bah_GlobalCommercialClientsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_4a8480fa-0ed1-4e57-a845-993d4c7ed015" xlink:to="loc_bah_GlobalCommercialClientsMember_feb462ee-7f17-4091-9ac3-fdbeec3cb7af" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_828eaa38-9087-454e-8986-608077486cf8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_d4855c47-89f3-429d-b410-539830b30792" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_828eaa38-9087-454e-8986-608077486cf8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_828eaa38-9087-454e-8986-608077486cf8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_828eaa38-9087-454e-8986-608077486cf8" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_828eaa38-9087-454e-8986-608077486cf8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_c103488f-6656-4084-a7ce-5eba4f8d41e2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_828eaa38-9087-454e-8986-608077486cf8" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_c103488f-6656-4084-a7ce-5eba4f8d41e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_dde14028-7cdd-424e-b15b-34a1c7a2e8d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_c103488f-6656-4084-a7ce-5eba4f8d41e2" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_dde14028-7cdd-424e-b15b-34a1c7a2e8d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_a04ff9f8-94c0-437b-acba-b716c39072b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SalesChannelThroughIntermediaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_c103488f-6656-4084-a7ce-5eba4f8d41e2" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_a04ff9f8-94c0-437b-acba-b716c39072b9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:type="extended" id="i41bfd6d6aa584d0d9fcaad639500d618_RevenueNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a226a80c-ad4c-4eb6-8bef-8dc12d9e53ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1ffc6016-6c52-4a1c-a99d-df1ae66eb4c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a226a80c-ad4c-4eb6-8bef-8dc12d9e53ab" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1ffc6016-6c52-4a1c-a99d-df1ae66eb4c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_52c8f81e-c53b-4aed-adb1-457898b73021" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a226a80c-ad4c-4eb6-8bef-8dc12d9e53ab" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_52c8f81e-c53b-4aed-adb1-457898b73021" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_8758fba9-6dbc-4b07-bcd2-8ad82b144459" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_52c8f81e-c53b-4aed-adb1-457898b73021" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_8758fba9-6dbc-4b07-bcd2-8ad82b144459" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueNarrativeDetails_1" xlink:type="simple" xlink:href="bah-20210331.xsd#RevenueNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueNarrativeDetails_1" xlink:type="extended" id="ica00e6ba53424995997e65c41525e05b_RevenueNarrativeDetails_1">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a226a80c-ad4c-4eb6-8bef-8dc12d9e53ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1ffc6016-6c52-4a1c-a99d-df1ae66eb4c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a226a80c-ad4c-4eb6-8bef-8dc12d9e53ab" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_1ffc6016-6c52-4a1c-a99d-df1ae66eb4c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_52c8f81e-c53b-4aed-adb1-457898b73021" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_a226a80c-ad4c-4eb6-8bef-8dc12d9e53ab" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_52c8f81e-c53b-4aed-adb1-457898b73021" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#EarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:type="extended" id="i033b48060b5345e79fbfae9583c63c31_EarningsPerShareDetails">
    <link:loc xlink:type="locator" xlink:label="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:href="bah-20210331.xsd#bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarnings_26b0dee8-4747-4ba0-a020-6dcb7a3f259c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_UndistributedEarnings_26b0dee8-4747-4ba0-a020-6dcb7a3f259c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_cc7345a8-ff89-4bb4-b7ce-dc15e45b9936" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_cc7345a8-ff89-4bb4-b7ce-dc15e45b9936" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsDiluted_47727f99-3144-4437-a03c-c79da76e2d5a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarningsDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_UndistributedEarningsDiluted_47727f99-3144-4437-a03c-c79da76e2d5a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_0b9220dd-2844-441a-999b-03a799b6a202" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_0b9220dd-2844-441a-999b-03a799b6a202" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_6d408dda-1720-4a75-8b10-785f1c87fd21" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_6d408dda-1720-4a75-8b10-785f1c87fd21" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_6554cf7e-45ec-4f6d-872f-69bf6309ec5f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_6554cf7e-45ec-4f6d-872f-69bf6309ec5f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_7a3828e4-968e-4a3b-81dd-baa4f9dcada2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_6554cf7e-45ec-4f6d-872f-69bf6309ec5f" xlink:to="loc_us-gaap_EarningsPerShareBasic_7a3828e4-968e-4a3b-81dd-baa4f9dcada2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_f9fd7383-e3b0-4b49-800d-f766d1e44f95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_6554cf7e-45ec-4f6d-872f-69bf6309ec5f" xlink:to="loc_us-gaap_EarningsPerShareDiluted_f9fd7383-e3b0-4b49-800d-f766d1e44f95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_711279e3-4f0f-47a6-be21-b58dd69c1b58" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_711279e3-4f0f-47a6-be21-b58dd69c1b58" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_664992e5-709c-4d10-960f-caf45575269a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsOfDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_PaymentsOfDividends_664992e5-709c-4d10-960f-caf45575269a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_7a2bf10e-29b1-421f-bb3e-b1662733dc9e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_7a2bf10e-29b1-421f-bb3e-b1662733dc9e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted_5a5eb0ce-740f-4795-a041-c3d852a8c6a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted_5a5eb0ce-740f-4795-a041-c3d852a8c6a9" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_40f514c8-518c-4d5d-b91f-857be64a3023" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_40f514c8-518c-4d5d-b91f-857be64a3023" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_e107100a-52e1-4be3-9d4c-0ce9ea2e0c54" xlink:href="bah-20210331.xsd#bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_d3af10cb-a57c-49d0-b88c-de10eca264e9" xlink:to="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_e107100a-52e1-4be3-9d4c-0ce9ea2e0c54" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b75d0c3e-3c2c-43ac-b41a-26f98e7d661a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bah_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_e107100a-52e1-4be3-9d4c-0ce9ea2e0c54" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b75d0c3e-3c2c-43ac-b41a-26f98e7d661a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b75d0c3e-3c2c-43ac-b41a-26f98e7d661a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b75d0c3e-3c2c-43ac-b41a-26f98e7d661a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_b75d0c3e-3c2c-43ac-b41a-26f98e7d661a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27914e5b-3b65-4695-9e12-302b008ac790" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_b75d0c3e-3c2c-43ac-b41a-26f98e7d661a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27914e5b-3b65-4695-9e12-302b008ac790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_3f05fff1-939a-4e07-8960-8cdeff5bba58" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27914e5b-3b65-4695-9e12-302b008ac790" xlink:to="loc_us-gaap_RestrictedStockMember_3f05fff1-939a-4e07-8960-8cdeff5bba58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_13ee8067-3ce4-480a-a53b-149db36155fe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_27914e5b-3b65-4695-9e12-302b008ac790" xlink:to="loc_us-gaap_EmployeeStockOptionMember_13ee8067-3ce4-480a-a53b-149db36155fe" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillandIntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#GoodwillandIntangibleAssetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillandIntangibleAssetsNarrativeDetails" xlink:type="extended" id="i54a96a5743cd431b849d8543f936f105_GoodwillandIntangibleAssetsNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_9cd3bcc5-7b9c-48b5-b17a-50b295e2ab6d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_98ddaa5b-9bff-45ff-92bd-dde64da4e991" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_9cd3bcc5-7b9c-48b5-b17a-50b295e2ab6d" xlink:to="loc_us-gaap_Goodwill_98ddaa5b-9bff-45ff-92bd-dde64da4e991" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_089a2c3f-d0e9-48ba-a807-1c3dba1e5737" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_9cd3bcc5-7b9c-48b5-b17a-50b295e2ab6d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_089a2c3f-d0e9-48ba-a807-1c3dba1e5737" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_1dabc3df-6968-4ca6-a9db-a187cc9bc555" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_9cd3bcc5-7b9c-48b5-b17a-50b295e2ab6d" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_1dabc3df-6968-4ca6-a9db-a187cc9bc555" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ef1b1db-539a-4d89-b161-7b49a7056d9d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_9cd3bcc5-7b9c-48b5-b17a-50b295e2ab6d" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ef1b1db-539a-4d89-b161-7b49a7056d9d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68410068-6e0e-4e34-be9c-be6f1a36bf2d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ef1b1db-539a-4d89-b161-7b49a7056d9d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68410068-6e0e-4e34-be9c-be6f1a36bf2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_68410068-6e0e-4e34-be9c-be6f1a36bf2d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68410068-6e0e-4e34-be9c-be6f1a36bf2d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_68410068-6e0e-4e34-be9c-be6f1a36bf2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38c46020-10a2-4ae9-9237-86d4e2fbca84" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_68410068-6e0e-4e34-be9c-be6f1a36bf2d" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38c46020-10a2-4ae9-9237-86d4e2fbca84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrderOrProductionBacklogMember_2d59846e-29b0-41c3-8ef3-debd7823179c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OrderOrProductionBacklogMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38c46020-10a2-4ae9-9237-86d4e2fbca84" xlink:to="loc_us-gaap_OrderOrProductionBacklogMember_2d59846e-29b0-41c3-8ef3-debd7823179c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_95efa9d5-5b2e-4b9b-92cb-2a6ba8d01cb8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_38c46020-10a2-4ae9-9237-86d4e2fbca84" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_95efa9d5-5b2e-4b9b-92cb-2a6ba8d01cb8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_965ba041-dad4-4a25-86ba-ad6607918a9a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_0ef1b1db-539a-4d89-b161-7b49a7056d9d" xlink:to="loc_srt_RangeAxis_965ba041-dad4-4a25-86ba-ad6607918a9a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_965ba041-dad4-4a25-86ba-ad6607918a9a_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_965ba041-dad4-4a25-86ba-ad6607918a9a" xlink:to="loc_srt_RangeMember_965ba041-dad4-4a25-86ba-ad6607918a9a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_3ce54c97-5bd4-43c5-9211-fa1e75f3c2df" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_965ba041-dad4-4a25-86ba-ad6607918a9a" xlink:to="loc_srt_RangeMember_3ce54c97-5bd4-43c5-9211-fa1e75f3c2df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_8c845ca7-46fa-4fba-9d8b-faa8e411c0a6" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3ce54c97-5bd4-43c5-9211-fa1e75f3c2df" xlink:to="loc_srt_MinimumMember_8c845ca7-46fa-4fba-9d8b-faa8e411c0a6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_71a5e168-3dc7-483e-be0a-791948f37193" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_3ce54c97-5bd4-43c5-9211-fa1e75f3c2df" xlink:to="loc_srt_MaximumMember_71a5e168-3dc7-483e-be0a-791948f37193" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/GoodwillandIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#GoodwillandIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/GoodwillandIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="extended" id="i99f120a7c9534ad3a98f7d10675de252_GoodwillandIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e8c84670-6814-4c17-bf98-5c3c4c899084" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_20024c05-b169-48e0-bac8-85e5a0500bb1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e8c84670-6814-4c17-bf98-5c3c4c899084" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_20024c05-b169-48e0-bac8-85e5a0500bb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_853f83e8-3035-4a9a-ab4a-3821b8621198" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_20024c05-b169-48e0-bac8-85e5a0500bb1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_853f83e8-3035-4a9a-ab4a-3821b8621198" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_02499ee5-93de-411b-9785-8811a8c36cd8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_20024c05-b169-48e0-bac8-85e5a0500bb1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_02499ee5-93de-411b-9785-8811a8c36cd8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_a0a2dac7-64d5-40fc-9408-9bedd8d4545a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNetAbstract_20024c05-b169-48e0-bac8-85e5a0500bb1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_a0a2dac7-64d5-40fc-9408-9bedd8d4545a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_b43e04e3-d417-4c22-a813-7027e31bc2ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e8c84670-6814-4c17-bf98-5c3c4c899084" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_b43e04e3-d417-4c22-a813-7027e31bc2ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_27d68ead-2dd5-4178-bffe-7fbdebae7037" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwillAbstract_b43e04e3-d417-4c22-a813-7027e31bc2ff" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_27d68ead-2dd5-4178-bffe-7fbdebae7037" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_92ad6675-ece3-4697-84cc-15f92bcc42a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e8c84670-6814-4c17-bf98-5c3c4c899084" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_92ad6675-ece3-4697-84cc-15f92bcc42a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_cdcaa93d-08b0-4a28-81dc-5222d5bdcd88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e8c84670-6814-4c17-bf98-5c3c4c899084" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_cdcaa93d-08b0-4a28-81dc-5222d5bdcd88" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9baffbf4-3554-4e59-be2c-a673b9db9d54" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_e8c84670-6814-4c17-bf98-5c3c4c899084" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9baffbf4-3554-4e59-be2c-a673b9db9d54" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_250bf721-6ed8-49c3-b0b6-f873f1422cba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9baffbf4-3554-4e59-be2c-a673b9db9d54" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_250bf721-6ed8-49c3-b0b6-f873f1422cba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_250bf721-6ed8-49c3-b0b6-f873f1422cba_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_250bf721-6ed8-49c3-b0b6-f873f1422cba" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_250bf721-6ed8-49c3-b0b6-f873f1422cba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae1289e4-958f-4977-903f-d4be36f53726" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_250bf721-6ed8-49c3-b0b6-f873f1422cba" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae1289e4-958f-4977-903f-d4be36f53726" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrderOrProductionBacklogMember_35664f3d-9a6e-4b9d-9467-d56cc579640a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OrderOrProductionBacklogMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae1289e4-958f-4977-903f-d4be36f53726" xlink:to="loc_us-gaap_OrderOrProductionBacklogMember_35664f3d-9a6e-4b9d-9467-d56cc579640a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_5e1b738e-5c76-4152-9b6d-cfe50af60796" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ae1289e4-958f-4977-903f-d4be36f53726" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_5e1b738e-5c76-4152-9b6d-cfe50af60796" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b1ef2c60-6eeb-46b0-9918-1cf2f63bc785" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_9baffbf4-3554-4e59-be2c-a673b9db9d54" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b1ef2c60-6eeb-46b0-9918-1cf2f63bc785" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b1ef2c60-6eeb-46b0-9918-1cf2f63bc785_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b1ef2c60-6eeb-46b0-9918-1cf2f63bc785" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b1ef2c60-6eeb-46b0-9918-1cf2f63bc785_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_c49248e9-68eb-404d-b99b-f25945fa63f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_b1ef2c60-6eeb-46b0-9918-1cf2f63bc785" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_c49248e9-68eb-404d-b99b-f25945fa63f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_6f27ee8a-7ab6-4285-beac-c4f1ab86cdd6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_c49248e9-68eb-404d-b99b-f25945fa63f7" xlink:to="loc_us-gaap_TradeNamesMember_6f27ee8a-7ab6-4285-beac-c4f1ab86cdd6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/PropertyandEquipmentNetDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#PropertyandEquipmentNetDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/PropertyandEquipmentNetDetails" xlink:type="extended" id="ib47b05ed3c9749608b35b39f4c0b0645_PropertyandEquipmentNetDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26e62c20-e58a-4bb7-a81e-46b5258d0728" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_94deceb7-7c61-4afe-95f5-876388de9cdc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26e62c20-e58a-4bb7-a81e-46b5258d0728" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_94deceb7-7c61-4afe-95f5-876388de9cdc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_8ad40db2-e6c7-40d4-ac00-b6de04e3c9db" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26e62c20-e58a-4bb7-a81e-46b5258d0728" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_8ad40db2-e6c7-40d4-ac00-b6de04e3c9db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_dae353c0-6440-4c09-b66f-984f44b69f78" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26e62c20-e58a-4bb7-a81e-46b5258d0728" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_dae353c0-6440-4c09-b66f-984f44b69f78" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_388c180a-0d32-4b92-9ce9-025c87df3ee9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_26e62c20-e58a-4bb7-a81e-46b5258d0728" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_388c180a-0d32-4b92-9ce9-025c87df3ee9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_abe99e19-9185-4084-a4fb-564f31a818e1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_388c180a-0d32-4b92-9ce9-025c87df3ee9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_abe99e19-9185-4084-a4fb-564f31a818e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_abe99e19-9185-4084-a4fb-564f31a818e1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_abe99e19-9185-4084-a4fb-564f31a818e1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_abe99e19-9185-4084-a4fb-564f31a818e1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50cacd90-cdd9-4ee1-8dcc-7627e3bed296" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_abe99e19-9185-4084-a4fb-564f31a818e1" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50cacd90-cdd9-4ee1-8dcc-7627e3bed296" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_b897e89f-e56a-4da3-b699-70dd02ddc408" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50cacd90-cdd9-4ee1-8dcc-7627e3bed296" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_b897e89f-e56a-4da3-b699-70dd02ddc408" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_f8bc72c7-3870-4694-be6f-7022902606c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50cacd90-cdd9-4ee1-8dcc-7627e3bed296" xlink:to="loc_us-gaap_ComputerEquipmentMember_f8bc72c7-3870-4694-be6f-7022902606c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_ff33e1fa-10fc-4090-92ee-c554bfb12b37" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_50cacd90-cdd9-4ee1-8dcc-7627e3bed296" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_ff33e1fa-10fc-4090-92ee-c554bfb12b37" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableandOtherAccruedExpensesDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#AccountsPayableandOtherAccruedExpensesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableandOtherAccruedExpensesDetails" xlink:type="extended" id="i007c04ac487d4b149498a012dd6a6a20_AccountsPayableandOtherAccruedExpensesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_813a0a23-4e14-4f9a-add0-f71ae8b05484" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_ad3af353-be9d-4f4b-b2ba-2daa1359735b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_813a0a23-4e14-4f9a-add0-f71ae8b05484" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_ad3af353-be9d-4f4b-b2ba-2daa1359735b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_460aad6c-2f35-4e5d-bfcf-569222b15ff1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_813a0a23-4e14-4f9a-add0-f71ae8b05484" xlink:to="loc_us-gaap_LossContingenciesTable_460aad6c-2f35-4e5d-bfcf-569222b15ff1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_b1d9ce61-3e06-4446-9ec9-29f8741a36b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_460aad6c-2f35-4e5d-bfcf-569222b15ff1" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_b1d9ce61-3e06-4446-9ec9-29f8741a36b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_b1d9ce61-3e06-4446-9ec9-29f8741a36b1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_b1d9ce61-3e06-4446-9ec9-29f8741a36b1" xlink:to="loc_us-gaap_LossContingencyNatureDomain_b1d9ce61-3e06-4446-9ec9-29f8741a36b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_eb805a78-a7c0-48fd-80f0-6f542fab8e57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_b1d9ce61-3e06-4446-9ec9-29f8741a36b1" xlink:to="loc_us-gaap_LossContingencyNatureDomain_eb805a78-a7c0-48fd-80f0-6f542fab8e57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfavorableRegulatoryActionMember_997fb6f6-325a-49ca-ac6a-ee16c2c43e06" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnfavorableRegulatoryActionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_eb805a78-a7c0-48fd-80f0-6f542fab8e57" xlink:to="loc_us-gaap_UnfavorableRegulatoryActionMember_997fb6f6-325a-49ca-ac6a-ee16c2c43e06" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleofDebtDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#DebtScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleofDebtDetails" xlink:type="extended" id="ia2986ba721e14ccba56f996c6854158c_DebtScheduleofDebtDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_ea793377-c941-4d5b-99be-c1e8c3677e90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtCurrentAndNoncurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ea793377-c941-4d5b-99be-c1e8c3677e90" xlink:to="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_995fecdf-8c8a-4495-afeb-1affe7ce1550" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_995fecdf-8c8a-4495-afeb-1affe7ce1550" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_6148a7c5-4d1b-42e3-85a7-c9f6eef17fde" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_6148a7c5-4d1b-42e3-85a7-c9f6eef17fde" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_ae8e48c0-576c-4c2c-9ea5-8fe5494e6753" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_ae8e48c0-576c-4c2c-9ea5-8fe5494e6753" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_26c4167e-615f-449b-ba84-c330a8dd6b5f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:to="loc_us-gaap_LongTermDebt_26c4167e-615f-449b-ba84-c330a8dd6b5f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_c93c5bf4-0cb5-4071-b9ff-11314b463443" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:to="loc_us-gaap_LongTermDebtCurrent_c93c5bf4-0cb5-4071-b9ff-11314b463443" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_a0b49b82-6503-4407-a52f-2ad7a7593bd7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_99df0ced-9288-407f-90d1-e06c4b20538a" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_a0b49b82-6503-4407-a52f-2ad7a7593bd7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_24edeb00-8e4c-4217-afbb-2dcfdf5c5a96" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ea793377-c941-4d5b-99be-c1e8c3677e90" xlink:to="loc_us-gaap_DebtInstrumentTable_24edeb00-8e4c-4217-afbb-2dcfdf5c5a96" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_69ef6476-926b-4e19-82ac-871649d0a7ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_24edeb00-8e4c-4217-afbb-2dcfdf5c5a96" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_69ef6476-926b-4e19-82ac-871649d0a7ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_69ef6476-926b-4e19-82ac-871649d0a7ac_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_69ef6476-926b-4e19-82ac-871649d0a7ac" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_69ef6476-926b-4e19-82ac-871649d0a7ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_6faffc52-956f-4951-b1b8-dbb06dcafb00" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_69ef6476-926b-4e19-82ac-871649d0a7ac" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_6faffc52-956f-4951-b1b8-dbb06dcafb00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_bb096b8e-a197-485b-a064-af56254dc835" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_6faffc52-956f-4951-b1b8-dbb06dcafb00" xlink:to="loc_us-gaap_SecuredDebtMember_bb096b8e-a197-485b-a064-af56254dc835" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_4bd2c1f2-7d63-4c50-a38c-2345579459b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_6faffc52-956f-4951-b1b8-dbb06dcafb00" xlink:to="loc_us-gaap_SeniorNotesMember_4bd2c1f2-7d63-4c50-a38c-2345579459b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_98fc964a-dd50-4bb6-92e2-10799d80ee26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_24edeb00-8e4c-4217-afbb-2dcfdf5c5a96" xlink:to="loc_us-gaap_DebtInstrumentAxis_98fc964a-dd50-4bb6-92e2-10799d80ee26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_98fc964a-dd50-4bb6-92e2-10799d80ee26_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_98fc964a-dd50-4bb6-92e2-10799d80ee26" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_98fc964a-dd50-4bb6-92e2-10799d80ee26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_98fc964a-dd50-4bb6-92e2-10799d80ee26" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheALoansMember_2c29583b-3f0a-485e-9fff-430b22c9d21c" xlink:href="bah-20210331.xsd#bah_TrancheALoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:to="loc_bah_TrancheALoansMember_2c29583b-3f0a-485e-9fff-430b22c9d21c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheBLoansMember_e61a10e4-49ce-4ef8-a898-e9f792cfe273" xlink:href="bah-20210331.xsd#bah_TrancheBLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:to="loc_bah_TrancheBLoansMember_e61a10e4-49ce-4ef8-a898-e9f792cfe273" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RevolverMember_2cd236ed-cc71-4d42-a7e3-0ee9fe03a5de" xlink:href="bah-20210331.xsd#bah_RevolverMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:to="loc_bah_RevolverMember_2cd236ed-cc71-4d42-a7e3-0ee9fe03a5de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SeniorNotesDue2028Member_a1b2a14c-5205-4c50-b116-cc79cc5085ab" xlink:href="bah-20210331.xsd#bah_SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:to="loc_bah_SeniorNotesDue2028Member_a1b2a14c-5205-4c50-b116-cc79cc5085ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SeniorNotesDue2025Member_d9821b57-fe8f-4a70-b6a8-cebe3a2dc18c" xlink:href="bah-20210331.xsd#bah_SeniorNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4d111bb5-cc32-4262-87db-7a12e9364a70" xlink:to="loc_bah_SeniorNotesDue2025Member_d9821b57-fe8f-4a70-b6a8-cebe3a2dc18c" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:type="extended" id="i0c0d50cb9e53488db85679fbc5874703_DebtNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_4c05b20e-cc55-4280-8ab3-525dde89e4b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_4c05b20e-cc55-4280-8ab3-525dde89e4b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_626497aa-32f1-46b5-bff4-c3c360bcba10" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_626497aa-32f1-46b5-bff4-c3c360bcba10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8b09821e-81d1-45e6-9024-bf4c049591ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_8b09821e-81d1-45e6-9024-bf4c049591ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_LongtermDebtMaximumExpandedLoanFacility_c78fabb9-7907-4c96-a546-54f80d2d88a0" xlink:href="bah-20210331.xsd#bah_LongtermDebtMaximumExpandedLoanFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_LongtermDebtMaximumExpandedLoanFacility_c78fabb9-7907-4c96-a546-54f80d2d88a0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired_0508a6dd-9761-4024-b657-636378c37c24" xlink:href="bah-20210331.xsd#bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired_0508a6dd-9761-4024-b657-636378c37c24" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DebtInstrumentNetSecuredLeverageRatioMaximum_38a156ac-4d85-441f-a026-1e4ffd555076" xlink:href="bah-20210331.xsd#bah_DebtInstrumentNetSecuredLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_DebtInstrumentNetSecuredLeverageRatioMaximum_38a156ac-4d85-441f-a026-1e4ffd555076" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_3fd4ebf5-92fc-445f-89b2-9ef332978d0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_3fd4ebf5-92fc-445f-89b2-9ef332978d0f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_6b97ce71-7a81-458d-8310-3e2ccf33008a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_6b97ce71-7a81-458d-8310-3e2ccf33008a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_051e3a96-fc90-4a25-864f-180bd2adf970" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_LineOfCredit_051e3a96-fc90-4a25-864f-180bd2adf970" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal_e4d7be56-e517-4828-b378-f4f5cb40f0e6" xlink:href="bah-20210331.xsd#bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal_e4d7be56-e517-4828-b378-f4f5cb40f0e6" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestPaid_19aadeca-c44e-4bb1-87b6-e8a75b4d4138" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_InterestPaid_19aadeca-c44e-4bb1-87b6-e8a75b4d4138" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_3a966e01-63f4-41c7-a9da-9ce8465b8b53" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DerivativeNotionalAmount_3a966e01-63f4-41c7-a9da-9ce8465b8b53" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_8f5e85df-dd65-4f3d-a5a5-dde7013b030e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_8f5e85df-dd65-4f3d-a5a5-dde7013b030e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_78f3ebe3-c7b4-4da6-a0bc-39b4271c471e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_78f3ebe3-c7b4-4da6-a0bc-39b4271c471e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_48948b3c-03ac-48e8-bd7d-39ee3080e6f5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_48948b3c-03ac-48e8-bd7d-39ee3080e6f5" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_9018217a-57eb-4c75-b251-43f8959f4aa5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed_9018217a-57eb-4c75-b251-43f8959f4aa5" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountOutstanding_f2104467-1a32-4b14-96e8-453d0b9bd69f" xlink:href="bah-20210331.xsd#bah_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountOutstanding_f2104467-1a32-4b14-96e8-453d0b9bd69f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DebtInstrumentRedemptionOfAggregatePrincipalAmountRedemptionPeriod_0ea7dc98-f54c-4d8d-8791-286eff16b673" xlink:href="bah-20210331.xsd#bah_DebtInstrumentRedemptionOfAggregatePrincipalAmountRedemptionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_DebtInstrumentRedemptionOfAggregatePrincipalAmountRedemptionPeriod_0ea7dc98-f54c-4d8d-8791-286eff16b673" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_8279f85d-5731-4018-bb25-d286751a30b0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_8279f85d-5731-4018-bb25-d286751a30b0" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_92104ee3-5015-4b34-8524-68eb096a0e20" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_92104ee3-5015-4b34-8524-68eb096a0e20" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_PaymentOfPremiumsAndWriteOffOfDebtIssuanceCosts_ad12a6cd-4d08-449d-9749-f662440a55f8" xlink:href="bah-20210331.xsd#bah_PaymentOfPremiumsAndWriteOffOfDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_bah_PaymentOfPremiumsAndWriteOffOfDebtIssuanceCosts_ad12a6cd-4d08-449d-9749-f662440a55f8" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_ee5719e8-43db-45ab-bc21-470876065d64" xlink:to="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_843e81a7-3318-4877-985f-863adb3fb8e6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_843e81a7-3318-4877-985f-863adb3fb8e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_843e81a7-3318-4877-985f-863adb3fb8e6_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_843e81a7-3318-4877-985f-863adb3fb8e6" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_843e81a7-3318-4877-985f-863adb3fb8e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d508dffe-2bdb-448f-8f0f-3e741443829f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_843e81a7-3318-4877-985f-863adb3fb8e6" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d508dffe-2bdb-448f-8f0f-3e741443829f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_d6a36840-c2fe-431a-9b41-25f796f30018" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d508dffe-2bdb-448f-8f0f-3e741443829f" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_d6a36840-c2fe-431a-9b41-25f796f30018" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_ba98ec49-5d1f-4c5f-b0ad-3c5d64637eaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d508dffe-2bdb-448f-8f0f-3e741443829f" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_ba98ec49-5d1f-4c5f-b0ad-3c5d64637eaf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_26dfec97-b8c4-4415-88a4-27de05817ba8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d508dffe-2bdb-448f-8f0f-3e741443829f" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_26dfec97-b8c4-4415-88a4-27de05817ba8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_4cda816b-7ad0-4940-9a8a-b876cdcb3686" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d508dffe-2bdb-448f-8f0f-3e741443829f" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodFourMember_4cda816b-7ad0-4940-9a8a-b876cdcb3686" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_f511d1b4-0055-4640-964f-7cd7169ec3a1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_DebtInstrumentAxis_f511d1b4-0055-4640-964f-7cd7169ec3a1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f511d1b4-0055-4640-964f-7cd7169ec3a1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_f511d1b4-0055-4640-964f-7cd7169ec3a1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f511d1b4-0055-4640-964f-7cd7169ec3a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_f511d1b4-0055-4640-964f-7cd7169ec3a1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheBLoansMember_e681c909-243f-42c9-b464-347b970f8c02" xlink:href="bah-20210331.xsd#bah_TrancheBLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:to="loc_bah_TrancheBLoansMember_e681c909-243f-42c9-b464-347b970f8c02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheALoansMember_282b14eb-13ca-4d47-b3cd-805b1d65f048" xlink:href="bah-20210331.xsd#bah_TrancheALoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:to="loc_bah_TrancheALoansMember_282b14eb-13ca-4d47-b3cd-805b1d65f048" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_072495ec-b319-44ae-90ba-d605732bcd1c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_072495ec-b319-44ae-90ba-d605732bcd1c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SeniorNotesDue2028Member_57caa4c8-7ba5-4405-b98a-05873a707676" xlink:href="bah-20210331.xsd#bah_SeniorNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:to="loc_bah_SeniorNotesDue2028Member_57caa4c8-7ba5-4405-b98a-05873a707676" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SeniorNotesDue2025Member_8a3012f6-5183-4e0a-92af-233da728989a" xlink:href="bah-20210331.xsd#bah_SeniorNotesDue2025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_acd626c3-647d-4aa0-bf5f-68673013e828" xlink:to="loc_bah_SeniorNotesDue2025Member_8a3012f6-5183-4e0a-92af-233da728989a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_1d1be167-3bc0-4d63-807b-e8ca0def8f3d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_1d1be167-3bc0-4d63-807b-e8ca0def8f3d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1d1be167-3bc0-4d63-807b-e8ca0def8f3d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1d1be167-3bc0-4d63-807b-e8ca0def8f3d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1d1be167-3bc0-4d63-807b-e8ca0def8f3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_cd13e062-5be4-4515-b550-9fa0b7f552a9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1d1be167-3bc0-4d63-807b-e8ca0def8f3d" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_cd13e062-5be4-4515-b550-9fa0b7f552a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_fe846343-5a4f-4456-9947-14745de4a803" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_cd13e062-5be4-4515-b550-9fa0b7f552a9" xlink:to="loc_us-gaap_SecuredDebtMember_fe846343-5a4f-4456-9947-14745de4a803" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_52481312-dbab-4901-a4f1-11036029f047" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_cd13e062-5be4-4515-b550-9fa0b7f552a9" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_52481312-dbab-4901-a4f1-11036029f047" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_1fcc7d3d-d982-4186-a808-6f9654510ff4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_cd13e062-5be4-4515-b550-9fa0b7f552a9" xlink:to="loc_us-gaap_LetterOfCreditMember_1fcc7d3d-d982-4186-a808-6f9654510ff4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_eab0d376-3cf7-4e31-94c2-8378a29de1f8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_cd13e062-5be4-4515-b550-9fa0b7f552a9" xlink:to="loc_us-gaap_SeniorNotesMember_eab0d376-3cf7-4e31-94c2-8378a29de1f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_9aa06b88-491d-4735-9c30-786fde78b919" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_VariableRateAxis_9aa06b88-491d-4735-9c30-786fde78b919" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_9aa06b88-491d-4735-9c30-786fde78b919_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_9aa06b88-491d-4735-9c30-786fde78b919" xlink:to="loc_us-gaap_VariableRateDomain_9aa06b88-491d-4735-9c30-786fde78b919_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_23112ad9-7906-448d-86a8-d6cd53a5862a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_9aa06b88-491d-4735-9c30-786fde78b919" xlink:to="loc_us-gaap_VariableRateDomain_23112ad9-7906-448d-86a8-d6cd53a5862a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3fe148a0-f669-4edf-8b8c-5b40524f47ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_23112ad9-7906-448d-86a8-d6cd53a5862a" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_3fe148a0-f669-4edf-8b8c-5b40524f47ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_6410b19e-49a1-4165-a807-3959c5a051c7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_23112ad9-7906-448d-86a8-d6cd53a5862a" xlink:to="loc_us-gaap_BaseRateMember_6410b19e-49a1-4165-a807-3959c5a051c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OvernightFederalFundsRateMember_958b3901-1c06-4051-ba2d-a1b60e07282c" xlink:href="bah-20210331.xsd#bah_OvernightFederalFundsRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_23112ad9-7906-448d-86a8-d6cd53a5862a" xlink:to="loc_bah_OvernightFederalFundsRateMember_958b3901-1c06-4051-ba2d-a1b60e07282c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AlternativeBaseRateABRMember_9f9c8d9a-3369-4b91-8119-5f1147fb7c38" xlink:href="bah-20210331.xsd#bah_AlternativeBaseRateABRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_23112ad9-7906-448d-86a8-d6cd53a5862a" xlink:to="loc_bah_AlternativeBaseRateABRMember_9f9c8d9a-3369-4b91-8119-5f1147fb7c38" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_227dc8e4-be0a-4f9a-b2d2-a59b72fb1301" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_227dc8e4-be0a-4f9a-b2d2-a59b72fb1301" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_227dc8e4-be0a-4f9a-b2d2-a59b72fb1301_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_227dc8e4-be0a-4f9a-b2d2-a59b72fb1301" xlink:to="loc_us-gaap_HedgingRelationshipDomain_227dc8e4-be0a-4f9a-b2d2-a59b72fb1301_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_5b47cb60-0145-40bc-b1a5-c93f180a48a4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_227dc8e4-be0a-4f9a-b2d2-a59b72fb1301" xlink:to="loc_us-gaap_HedgingRelationshipDomain_5b47cb60-0145-40bc-b1a5-c93f180a48a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_6f045a41-2eca-4457-8a2c-6aa15125e1f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_5b47cb60-0145-40bc-b1a5-c93f180a48a4" xlink:to="loc_us-gaap_CashFlowHedgingMember_6f045a41-2eca-4457-8a2c-6aa15125e1f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_b178e308-5569-4a09-a06b-a0c6b579cbc3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_b178e308-5569-4a09-a06b-a0c6b579cbc3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_b178e308-5569-4a09-a06b-a0c6b579cbc3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_b178e308-5569-4a09-a06b-a0c6b579cbc3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_b178e308-5569-4a09-a06b-a0c6b579cbc3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3e1419d5-766d-4d5f-9d41-f47dbddd8e47" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_b178e308-5569-4a09-a06b-a0c6b579cbc3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3e1419d5-766d-4d5f-9d41-f47dbddd8e47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_0d59bedd-35f5-41ae-8d85-93b1bce2e387" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3e1419d5-766d-4d5f-9d41-f47dbddd8e47" xlink:to="loc_us-gaap_InterestRateSwapMember_0d59bedd-35f5-41ae-8d85-93b1bce2e387" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_b34701cc-046c-4afc-b3b0-e1c1984c5c95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_us-gaap_HedgingDesignationAxis_b34701cc-046c-4afc-b3b0-e1c1984c5c95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_b34701cc-046c-4afc-b3b0-e1c1984c5c95_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_b34701cc-046c-4afc-b3b0-e1c1984c5c95" xlink:to="loc_us-gaap_HedgingDesignationDomain_b34701cc-046c-4afc-b3b0-e1c1984c5c95_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_a46b1ee6-6ce7-47b4-9ca7-889a3092633a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_b34701cc-046c-4afc-b3b0-e1c1984c5c95" xlink:to="loc_us-gaap_HedgingDesignationDomain_a46b1ee6-6ce7-47b4-9ca7-889a3092633a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_fcf3d699-3c16-46e3-8966-91049664d279" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_a46b1ee6-6ce7-47b4-9ca7-889a3092633a" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_fcf3d699-3c16-46e3-8966-91049664d279" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_227925ed-c07f-46b4-ba15-22e3beffb1a5" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6678b322-78d8-4b1f-b467-de2fd394ace3" xlink:to="loc_srt_RangeAxis_227925ed-c07f-46b4-ba15-22e3beffb1a5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_227925ed-c07f-46b4-ba15-22e3beffb1a5_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_227925ed-c07f-46b4-ba15-22e3beffb1a5" xlink:to="loc_srt_RangeMember_227925ed-c07f-46b4-ba15-22e3beffb1a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_e26c2e96-8504-4906-a367-a6c8fa8be98a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_227925ed-c07f-46b4-ba15-22e3beffb1a5" xlink:to="loc_srt_RangeMember_e26c2e96-8504-4906-a367-a6c8fa8be98a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_caca6da9-0c4e-4324-9e24-ae6384cf0550" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e26c2e96-8504-4906-a367-a6c8fa8be98a" xlink:to="loc_srt_MinimumMember_caca6da9-0c4e-4324-9e24-ae6384cf0550" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_73c007b2-3dfa-49d2-acca-c6a922039424" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_e26c2e96-8504-4906-a367-a6c8fa8be98a" xlink:to="loc_srt_MaximumMember_73c007b2-3dfa-49d2-acca-c6a922039424" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleofFutureDebtPrincipalRepaymentsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#DebtScheduleofFutureDebtPrincipalRepaymentsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleofFutureDebtPrincipalRepaymentsDetails" xlink:type="extended" id="ia3fd9b44658143e2bd42a3bbbb6c1c3e_DebtScheduleofFutureDebtPrincipalRepaymentsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_0ee2a6a2-d1c5-4fff-a846-74cc89331aa6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_0ee2a6a2-d1c5-4fff-a846-74cc89331aa6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7b26524e-2d06-40aa-9e45-9ac53fa30273" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths_7b26524e-2d06-40aa-9e45-9ac53fa30273" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_330f592c-dbcf-4d93-843e-8f7a0afd0fd3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo_330f592c-dbcf-4d93-843e-8f7a0afd0fd3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_cbfe7d8d-1a7d-41b9-9477-6c56b84b7870" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree_cbfe7d8d-1a7d-41b9-9477-6c56b84b7870" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_65aebb72-e0a4-42fc-b19b-377f421a506c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour_65aebb72-e0a4-42fc-b19b-377f421a506c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_eb08ea43-a8ed-412d-9a18-fa33dcf7453d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive_eb08ea43-a8ed-412d-9a18-fa33dcf7453d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_1b4766ec-e887-4c67-b494-f7279bfb892a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive_1b4766ec-e887-4c67-b494-f7279bfb892a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_3dad9e92-fb08-433d-8afa-e6f361e3d442" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_457befb7-68f5-4e27-b1f2-611b56fa3c40" xlink:to="loc_us-gaap_DebtInstrumentTable_3dad9e92-fb08-433d-8afa-e6f361e3d442" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_438d2f48-9f68-4e80-b7ad-f30960d78018" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3dad9e92-fb08-433d-8afa-e6f361e3d442" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_438d2f48-9f68-4e80-b7ad-f30960d78018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_438d2f48-9f68-4e80-b7ad-f30960d78018_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_438d2f48-9f68-4e80-b7ad-f30960d78018" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_438d2f48-9f68-4e80-b7ad-f30960d78018_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_03b38c5f-f7ed-4c10-99f0-1adcb6e71771" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_438d2f48-9f68-4e80-b7ad-f30960d78018" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_03b38c5f-f7ed-4c10-99f0-1adcb6e71771" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_d900bf28-91e8-40ad-a950-4ae1d50c9100" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_03b38c5f-f7ed-4c10-99f0-1adcb6e71771" xlink:to="loc_us-gaap_SeniorNotesMember_d900bf28-91e8-40ad-a950-4ae1d50c9100" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_186cc8e4-08ad-47da-82a0-1715862312d4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3dad9e92-fb08-433d-8afa-e6f361e3d442" xlink:to="loc_us-gaap_DebtInstrumentAxis_186cc8e4-08ad-47da-82a0-1715862312d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_186cc8e4-08ad-47da-82a0-1715862312d4_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_186cc8e4-08ad-47da-82a0-1715862312d4" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_186cc8e4-08ad-47da-82a0-1715862312d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_34fa754b-caed-4266-8c03-ef501173df7b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_186cc8e4-08ad-47da-82a0-1715862312d4" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_34fa754b-caed-4266-8c03-ef501173df7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheALoansMember_be480026-2d71-4170-ba7f-0c9cac6825b4" xlink:href="bah-20210331.xsd#bah_TrancheALoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_34fa754b-caed-4266-8c03-ef501173df7b" xlink:to="loc_bah_TrancheALoansMember_be480026-2d71-4170-ba7f-0c9cac6825b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheBLoansMember_cb4e8dcd-7fbb-4c1d-adb2-70da4b1b5f36" xlink:href="bah-20210331.xsd#bah_TrancheBLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_34fa754b-caed-4266-8c03-ef501173df7b" xlink:to="loc_bah_TrancheBLoansMember_cb4e8dcd-7fbb-4c1d-adb2-70da4b1b5f36" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleofDetailofInterestExpenseDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#DebtScheduleofDetailofInterestExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleofDetailofInterestExpenseDetails" xlink:type="extended" id="ice2641c53f204541b233c771bb460a98_DebtScheduleofDetailofInterestExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_2feb28b1-df4f-4f8d-9642-a85b96209a15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_us-gaap_InterestExpenseDebt_2feb28b1-df4f-4f8d-9642-a85b96209a15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DeferredPaymentObligationInterestPayment_95a68251-b68c-4f2c-a3c1-525a277f27b2" xlink:href="bah-20210331.xsd#bah_DeferredPaymentObligationInterestPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_bah_DeferredPaymentObligationInterestPayment_95a68251-b68c-4f2c-a3c1-525a277f27b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_70c1021d-a296-4245-8f4c-e051ec5d1af5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_70c1021d-a296-4245-8f4c-e051ec5d1af5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_InterestExpenseDebtInterestSwap_6d640af2-daec-4517-a53a-9dca4cf8f968" xlink:href="bah-20210331.xsd#bah_InterestExpenseDebtInterestSwap"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_bah_InterestExpenseDebtInterestSwap_6d640af2-daec-4517-a53a-9dca4cf8f968" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_InterestIncomeExpenseOther_ff467334-4d99-4843-85d3-c6650b63dd1e" xlink:href="bah-20210331.xsd#bah_InterestIncomeExpenseOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_bah_InterestIncomeExpenseOther_ff467334-4d99-4843-85d3-c6650b63dd1e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_e8c9af6c-3016-49eb-9f70-b469c7218023" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_us-gaap_InterestExpense_e8c9af6c-3016-49eb-9f70-b469c7218023" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DeferredPaymentObligationPaymentPeriod_214986df-6137-47a1-b50c-5b41cdae4ff8" xlink:href="bah-20210331.xsd#bah_DeferredPaymentObligationPaymentPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_bah_DeferredPaymentObligationPaymentPeriod_214986df-6137-47a1-b50c-5b41cdae4ff8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_196b4ec6-980f-4759-bd45-2ed2e62d8ecb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6bf8a6bc-844b-47e6-9213-201c46618366" xlink:to="loc_us-gaap_DebtInstrumentTable_196b4ec6-980f-4759-bd45-2ed2e62d8ecb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_39f264ee-69c5-4bb3-b79e-5b927572db43" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_196b4ec6-980f-4759-bd45-2ed2e62d8ecb" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_39f264ee-69c5-4bb3-b79e-5b927572db43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_39f264ee-69c5-4bb3-b79e-5b927572db43_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_39f264ee-69c5-4bb3-b79e-5b927572db43" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_39f264ee-69c5-4bb3-b79e-5b927572db43_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_5ce69da2-0aa7-40c9-8d8a-552236315684" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_39f264ee-69c5-4bb3-b79e-5b927572db43" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_5ce69da2-0aa7-40c9-8d8a-552236315684" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_928ba7e6-95e7-4b4b-9cd9-d482a9c56106" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5ce69da2-0aa7-40c9-8d8a-552236315684" xlink:to="loc_us-gaap_SecuredDebtMember_928ba7e6-95e7-4b4b-9cd9-d482a9c56106" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_93d2004e-947a-4852-986a-d11f4dad3e9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5ce69da2-0aa7-40c9-8d8a-552236315684" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_93d2004e-947a-4852-986a-d11f4dad3e9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_af8f55d9-9b74-4471-b59b-54cb102bc185" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_5ce69da2-0aa7-40c9-8d8a-552236315684" xlink:to="loc_us-gaap_SeniorNotesMember_af8f55d9-9b74-4471-b59b-54cb102bc185" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7263b359-44d2-4e4f-95b0-8d79d85fb61a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_196b4ec6-980f-4759-bd45-2ed2e62d8ecb" xlink:to="loc_us-gaap_DebtInstrumentAxis_7263b359-44d2-4e4f-95b0-8d79d85fb61a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7263b359-44d2-4e4f-95b0-8d79d85fb61a_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7263b359-44d2-4e4f-95b0-8d79d85fb61a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7263b359-44d2-4e4f-95b0-8d79d85fb61a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_8a908ca7-aaf0-4825-99ab-2772946fa21f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7263b359-44d2-4e4f-95b0-8d79d85fb61a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_8a908ca7-aaf0-4825-99ab-2772946fa21f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheALoansMember_0e02d82f-18ac-469a-b32e-d358b80e0d6e" xlink:href="bah-20210331.xsd#bah_TrancheALoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a908ca7-aaf0-4825-99ab-2772946fa21f" xlink:to="loc_bah_TrancheALoansMember_0e02d82f-18ac-469a-b32e-d358b80e0d6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TrancheBLoansMember_368428e6-6182-4791-96f0-95d51e60fdea" xlink:href="bah-20210331.xsd#bah_TrancheBLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_8a908ca7-aaf0-4825-99ab-2772946fa21f" xlink:to="loc_bah_TrancheBLoansMember_368428e6-6182-4791-96f0-95d51e60fdea" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#DerivativesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesNarrativeDetails" xlink:type="extended" id="i4bd5930d0f9b4e34be8540a0f80643e9_DerivativesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_d8e6840b-bbea-412c-b881-d89be4da82be" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_d4b7d3c5-138e-4c65-9ccf-a4a6c41cd3c3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d8e6840b-bbea-412c-b881-d89be4da82be" xlink:to="loc_us-gaap_DerivativeNotionalAmount_d4b7d3c5-138e-4c65-9ccf-a4a6c41cd3c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_c3c79d12-a127-4e45-85ab-5750e054c5d5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d8e6840b-bbea-412c-b881-d89be4da82be" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_c3c79d12-a127-4e45-85ab-5750e054c5d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_e2e4dd59-d57e-4f1f-9f3c-75488fe9e193" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d8e6840b-bbea-412c-b881-d89be4da82be" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_e2e4dd59-d57e-4f1f-9f3c-75488fe9e193" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_4b298a0d-0b49-495e-a41d-6f2555fd1739" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_d8e6840b-bbea-412c-b881-d89be4da82be" xlink:to="loc_us-gaap_DerivativeTable_4b298a0d-0b49-495e-a41d-6f2555fd1739" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_ac311e9a-38e3-4956-82ba-34acaacd18b8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4b298a0d-0b49-495e-a41d-6f2555fd1739" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_ac311e9a-38e3-4956-82ba-34acaacd18b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_ac311e9a-38e3-4956-82ba-34acaacd18b8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_ac311e9a-38e3-4956-82ba-34acaacd18b8" xlink:to="loc_us-gaap_HedgingRelationshipDomain_ac311e9a-38e3-4956-82ba-34acaacd18b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_370c1314-54cf-48fc-a66e-18f86849bbea" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_ac311e9a-38e3-4956-82ba-34acaacd18b8" xlink:to="loc_us-gaap_HedgingRelationshipDomain_370c1314-54cf-48fc-a66e-18f86849bbea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_27885edf-514a-4793-b7b6-9338151d8c95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_370c1314-54cf-48fc-a66e-18f86849bbea" xlink:to="loc_us-gaap_CashFlowHedgingMember_27885edf-514a-4793-b7b6-9338151d8c95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_8ed71ec4-dc1a-433d-8e7e-26e9e411a968" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4b298a0d-0b49-495e-a41d-6f2555fd1739" xlink:to="loc_us-gaap_HedgingDesignationAxis_8ed71ec4-dc1a-433d-8e7e-26e9e411a968" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_8ed71ec4-dc1a-433d-8e7e-26e9e411a968_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_8ed71ec4-dc1a-433d-8e7e-26e9e411a968" xlink:to="loc_us-gaap_HedgingDesignationDomain_8ed71ec4-dc1a-433d-8e7e-26e9e411a968_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_1d2defaa-c645-4d85-a37c-0453a4a43545" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_8ed71ec4-dc1a-433d-8e7e-26e9e411a968" xlink:to="loc_us-gaap_HedgingDesignationDomain_1d2defaa-c645-4d85-a37c-0453a4a43545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_95311dbe-9ca0-42d4-af3e-1b86e371c42b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_1d2defaa-c645-4d85-a37c-0453a4a43545" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_95311dbe-9ca0-42d4-af3e-1b86e371c42b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_5522a1dd-27e7-418f-9b18-5b66927347f9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4b298a0d-0b49-495e-a41d-6f2555fd1739" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_5522a1dd-27e7-418f-9b18-5b66927347f9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5522a1dd-27e7-418f-9b18-5b66927347f9_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_5522a1dd-27e7-418f-9b18-5b66927347f9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5522a1dd-27e7-418f-9b18-5b66927347f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c8989279-fc60-4916-9cb3-7b706b228afc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_5522a1dd-27e7-418f-9b18-5b66927347f9" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c8989279-fc60-4916-9cb3-7b706b228afc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_3fb63afc-08dc-43a3-b20c-78cea459de01" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_c8989279-fc60-4916-9cb3-7b706b228afc" xlink:to="loc_us-gaap_InterestRateSwapMember_3fb63afc-08dc-43a3-b20c-78cea459de01" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_8643a46e-86e8-4584-9097-0b21b1464624" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_4b298a0d-0b49-495e-a41d-6f2555fd1739" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_8643a46e-86e8-4584-9097-0b21b1464624" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_8643a46e-86e8-4584-9097-0b21b1464624_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_8643a46e-86e8-4584-9097-0b21b1464624" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_8643a46e-86e8-4584-9097-0b21b1464624_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_f28f1d83-4fe4-48b8-a088-74a673c96b9c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_8643a46e-86e8-4584-9097-0b21b1464624" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_f28f1d83-4fe4-48b8-a088-74a673c96b9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_6d5d104e-98a4-426d-931f-0a3c8fd59f90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherCurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_f28f1d83-4fe4-48b8-a088-74a673c96b9c" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_6d5d104e-98a4-426d-931f-0a3c8fd59f90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_31a9b1a7-c83b-460a-b162-a6787a8a658b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_f28f1d83-4fe4-48b8-a088-74a673c96b9c" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_31a9b1a7-c83b-460a-b162-a6787a8a658b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesScheduleofEffectofDerivativesonFinancialStatementsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#DerivativesScheduleofEffectofDerivativesonFinancialStatementsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesScheduleofEffectofDerivativesonFinancialStatementsDetails" xlink:type="extended" id="ia88094ce144b42c1afa1b53192562334_DerivativesScheduleofEffectofDerivativesonFinancialStatementsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_375e4d05-d817-4c88-9d1d-1c38b9db8171" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_cad8aac4-b38a-4722-ae68-6c0d031e7d7b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_375e4d05-d817-4c88-9d1d-1c38b9db8171" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_cad8aac4-b38a-4722-ae68-6c0d031e7d7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_658e88a7-a301-441f-879f-f729b3a859ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_375e4d05-d817-4c88-9d1d-1c38b9db8171" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_658e88a7-a301-441f-879f-f729b3a859ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_f6f6e2eb-7750-49c2-a02a-b87cdef13913" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_375e4d05-d817-4c88-9d1d-1c38b9db8171" xlink:to="loc_us-gaap_InterestExpense_f6f6e2eb-7750-49c2-a02a-b87cdef13913" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_0d2a480e-2787-4a75-b81b-6f63e4bfd875" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_375e4d05-d817-4c88-9d1d-1c38b9db8171" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_0d2a480e-2787-4a75-b81b-6f63e4bfd875" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_f65333e3-d32c-4f24-afb1-c317af4c4e79" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_0d2a480e-2787-4a75-b81b-6f63e4bfd875" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_f65333e3-d32c-4f24-afb1-c317af4c4e79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f65333e3-d32c-4f24-afb1-c317af4c4e79_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_f65333e3-d32c-4f24-afb1-c317af4c4e79" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f65333e3-d32c-4f24-afb1-c317af4c4e79_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_07c0d707-f67a-4bc8-8772-31420186f1c7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_f65333e3-d32c-4f24-afb1-c317af4c4e79" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_07c0d707-f67a-4bc8-8772-31420186f1c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_43cd3c45-f53b-4dcf-a7b5-0aebedd12afb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_07c0d707-f67a-4bc8-8772-31420186f1c7" xlink:to="loc_us-gaap_InterestRateSwapMember_43cd3c45-f53b-4dcf-a7b5-0aebedd12afb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_ef7b85d6-ff0a-4951-8908-85fd44a46d77" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_0d2a480e-2787-4a75-b81b-6f63e4bfd875" xlink:to="loc_us-gaap_HedgingDesignationAxis_ef7b85d6-ff0a-4951-8908-85fd44a46d77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ef7b85d6-ff0a-4951-8908-85fd44a46d77_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_ef7b85d6-ff0a-4951-8908-85fd44a46d77" xlink:to="loc_us-gaap_HedgingDesignationDomain_ef7b85d6-ff0a-4951-8908-85fd44a46d77_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_cb41c407-f630-4e79-9d04-796562a3eb68" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_ef7b85d6-ff0a-4951-8908-85fd44a46d77" xlink:to="loc_us-gaap_HedgingDesignationDomain_cb41c407-f630-4e79-9d04-796562a3eb68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_b9cdea53-6a25-4e90-b7e8-b25df6ad855f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_cb41c407-f630-4e79-9d04-796562a3eb68" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_b9cdea53-6a25-4e90-b7e8-b25df6ad855f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_98c3d4a1-98b3-4978-b5a5-3d53e14e1ffb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_0d2a480e-2787-4a75-b81b-6f63e4bfd875" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_98c3d4a1-98b3-4978-b5a5-3d53e14e1ffb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_98c3d4a1-98b3-4978-b5a5-3d53e14e1ffb_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_98c3d4a1-98b3-4978-b5a5-3d53e14e1ffb" xlink:to="loc_us-gaap_HedgingRelationshipDomain_98c3d4a1-98b3-4978-b5a5-3d53e14e1ffb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_3c175517-7d35-46a1-996c-fed0a578f4ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_98c3d4a1-98b3-4978-b5a5-3d53e14e1ffb" xlink:to="loc_us-gaap_HedgingRelationshipDomain_3c175517-7d35-46a1-996c-fed0a578f4ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_ad6ef75e-9034-4614-82a8-27b21f838921" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_3c175517-7d35-46a1-996c-fed0a578f4ac" xlink:to="loc_us-gaap_CashFlowHedgingMember_ad6ef75e-9034-4614-82a8-27b21f838921" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended" id="id3c033ae59e14253b8d3283e9ba4cd7c_IncomeTaxesNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivableNoncurrent_cbece82a-6c25-42f0-ae5f-01a696bfaa04" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxesReceivableNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_IncomeTaxesReceivableNoncurrent_cbece82a-6c25-42f0-ae5f-01a696bfaa04" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DeferredTaxLiabilityChangeInAccountingPolicy_abdbda9b-9420-4b6b-8ae2-ee4e0110e55f" xlink:href="bah-20210331.xsd#bah_DeferredTaxLiabilityChangeInAccountingPolicy"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_bah_DeferredTaxLiabilityChangeInAccountingPolicy_abdbda9b-9420-4b6b-8ae2-ee4e0110e55f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_IncomeTaxExpenseBenefitRemeasurementOfNetOperatingLossesCARESAct_f3dcf5f3-7771-4a4d-8bb4-1c1f7638af44" xlink:href="bah-20210331.xsd#bah_IncomeTaxExpenseBenefitRemeasurementOfNetOperatingLossesCARESAct"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_bah_IncomeTaxExpenseBenefitRemeasurementOfNetOperatingLossesCARESAct_f3dcf5f3-7771-4a4d-8bb4-1c1f7638af44" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_ef094c17-bdaa-4e8b-bc8d-f629fa8c7639" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_OperatingLossCarryforwards_ef094c17-bdaa-4e8b-bc8d-f629fa8c7639" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal_46b5bafb-1a3f-431b-8c9a-5e174679d506" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal_46b5bafb-1a3f-431b-8c9a-5e174679d506" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_LiabilityForUncertaintyInIncomeTaxes_ee3c8480-dffd-46ba-8196-ed5c198461a0" xlink:href="bah-20210331.xsd#bah_LiabilityForUncertaintyInIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_bah_LiabilityForUncertaintyInIncomeTaxes_ee3c8480-dffd-46ba-8196-ed5c198461a0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_7e207d6a-eac7-4bb4-b153-a01eccfbe96b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate_7e207d6a-eac7-4bb4-b153-a01eccfbe96b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedTaxBenefitsThatImpactDeferredTaxLiabilities_357ff8f0-8585-4d85-bbd5-c1422290a962" xlink:href="bah-20210331.xsd#bah_UnrecognizedTaxBenefitsThatImpactDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_bah_UnrecognizedTaxBenefitsThatImpactDeferredTaxLiabilities_357ff8f0-8585-4d85-bbd5-c1422290a962" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedTaxBenefitsReasonablyPossibleReductionResultingfromLapseofApplicableStatuteofLimitations_a5015cdd-6543-4f29-99bb-d814878bc46d" xlink:href="bah-20210331.xsd#bah_UnrecognizedTaxBenefitsReasonablyPossibleReductionResultingfromLapseofApplicableStatuteofLimitations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_bah_UnrecognizedTaxBenefitsReasonablyPossibleReductionResultingfromLapseofApplicableStatuteofLimitations_a5015cdd-6543-4f29-99bb-d814878bc46d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_a08bc9e9-7531-46cf-89e3-e6347b3110d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_a08bc9e9-7531-46cf-89e3-e6347b3110d0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_37c246dc-417d-47f4-9c1a-178b667ea19c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_37c246dc-417d-47f4-9c1a-178b667ea19c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss_c712b63a-7dba-4a38-9f02-6ba54015fe4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss_c712b63a-7dba-4a38-9f02-6ba54015fe4e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_ee7d8856-5adc-4b4a-8147-d97f90d5322f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_ee7d8856-5adc-4b4a-8147-d97f90d5322f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_db388f68-fef6-40f4-b613-1be78d66ae3c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions_db388f68-fef6-40f4-b613-1be78d66ae3c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_99e7f742-c3da-4801-8c28-e70979a737da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions_99e7f742-c3da-4801-8c28-e70979a737da" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromCurrentPeriodTaxPositions_721cc2af-9005-45eb-9b98-1be80f073600" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromCurrentPeriodTaxPositions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromCurrentPeriodTaxPositions_721cc2af-9005-45eb-9b98-1be80f073600" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_d48e89ce-d221-4c7a-babc-aae52b448ffe" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities_d48e89ce-d221-4c7a-babc-aae52b448ffe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_9dc58edd-9899-4364-a798-c9d6a849fc84" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward_3b21467c-8418-4a5d-ba94-631ef20f5313" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_9dc58edd-9899-4364-a798-c9d6a849fc84" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_a33434e7-f4e0-4422-bdeb-b911affffab9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_b9c800c6-fd58-4b6d-9149-7d9ef59fbee0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_1793adf2-8990-4c3a-9c3b-75fba38f822a" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_b9c800c6-fd58-4b6d-9149-7d9ef59fbee0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodAxis_d188e543-1762-4110-b927-328858e658f0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_b9c800c6-fd58-4b6d-9149-7d9ef59fbee0" xlink:to="loc_us-gaap_TaxPeriodAxis_d188e543-1762-4110-b927-328858e658f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_d188e543-1762-4110-b927-328858e658f0_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_d188e543-1762-4110-b927-328858e658f0" xlink:to="loc_us-gaap_TaxPeriodDomain_d188e543-1762-4110-b927-328858e658f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxPeriodDomain_f4c3d5ad-402f-40ca-8051-267caa15aa69" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TaxPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_d188e543-1762-4110-b927-328858e658f0" xlink:to="loc_us-gaap_TaxPeriodDomain_f4c3d5ad-402f-40ca-8051-267caa15aa69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TaxYear2022AndThereafterMember_820d0bdf-5f19-4d6f-ade2-bda0fe2691dc" xlink:href="bah-20210331.xsd#bah_TaxYear2022AndThereafterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_f4c3d5ad-402f-40ca-8051-267caa15aa69" xlink:to="loc_bah_TaxYear2022AndThereafterMember_820d0bdf-5f19-4d6f-ade2-bda0fe2691dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TaxYears20132015Member_12e521aa-8245-41e0-bb07-52fb71ab9d9b" xlink:href="bah-20210331.xsd#bah_TaxYears20132015Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_f4c3d5ad-402f-40ca-8051-267caa15aa69" xlink:to="loc_bah_TaxYears20132015Member_12e521aa-8245-41e0-bb07-52fb71ab9d9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_TaxYears20162021Member_b1159786-5c28-41f0-bf83-02fb7f306723" xlink:href="bah-20210331.xsd#bah_TaxYears20162021Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_f4c3d5ad-402f-40ca-8051-267caa15aa69" xlink:to="loc_bah_TaxYears20162021Member_b1159786-5c28-41f0-bf83-02fb7f306723" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_36b044eb-51b8-44c7-a899-4ddcec3447f3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_b9c800c6-fd58-4b6d-9149-7d9ef59fbee0" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_36b044eb-51b8-44c7-a899-4ddcec3447f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_36b044eb-51b8-44c7-a899-4ddcec3447f3_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_36b044eb-51b8-44c7-a899-4ddcec3447f3" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_36b044eb-51b8-44c7-a899-4ddcec3447f3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_41c83aeb-23c3-42ab-831c-97479f676106" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_36b044eb-51b8-44c7-a899-4ddcec3447f3" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_41c83aeb-23c3-42ab-831c-97479f676106" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_bd7a159d-d1df-4ffb-a395-feec30547f62" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_41c83aeb-23c3-42ab-831c-97479f676106" xlink:to="loc_us-gaap_DomesticCountryMember_bd7a159d-d1df-4ffb-a395-feec30547f62" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_1fcfcfb9-22ac-4180-998e-b6f088c5c945" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_41c83aeb-23c3-42ab-831c-97479f676106" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_1fcfcfb9-22ac-4180-998e-b6f088c5c945" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_04b051ab-c483-4c7c-8b15-585615eb0cc6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_41c83aeb-23c3-42ab-831c-97479f676106" xlink:to="loc_us-gaap_ForeignCountryMember_04b051ab-c483-4c7c-8b15-585615eb0cc6" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#EmployeeBenefitPlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansNarrativeDetails" xlink:type="extended" id="i428d880c724c423dbc7f0706d0840cc5_EmployeeBenefitPlansNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_0b35e562-342f-4270-8f04-3b9323cb3883" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_0b35e562-342f-4270-8f04-3b9323cb3883" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_9bfe5e70-4a24-42de-8ed9-791247da9dd0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_9bfe5e70-4a24-42de-8ed9-791247da9dd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount_85b3c764-bb86-4beb-9c4c-f8dd01e933bd" xlink:href="bah-20210331.xsd#bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount_85b3c764-bb86-4beb-9c4c-f8dd01e933bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_5c0ff4cf-5e59-40a3-8d48-c96f869f9315" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_5c0ff4cf-5e59-40a3-8d48-c96f869f9315" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_864939dc-0fb2-4c6b-923c-78f17397e399" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_864939dc-0fb2-4c6b-923c-78f17397e399" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_4d924da9-d063-45c1-adea-cfe7a1e55189" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_4d924da9-d063-45c1-adea-cfe7a1e55189" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_3d623aba-4e70-49aa-804e-4940858201ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_3d623aba-4e70-49aa-804e-4940858201ac" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax_95284c87-b3a1-4520-b82c-3c724f35a3b7" xlink:href="bah-20210331.xsd#bah_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_bah_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax_95284c87-b3a1-4520-b82c-3c724f35a3b7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_f2c4cb7c-647e-4558-aaa9-9f440caa7edb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PostemploymentBenefitsLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_f2c4cb7c-647e-4558-aaa9-9f440caa7edb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_IncreaseDecreaseInPostemploymentBenefitsLiabilityNoncurrent_0373defb-2b6a-41ac-9cec-4254d0da8c2f" xlink:href="bah-20210331.xsd#bah_IncreaseDecreaseInPostemploymentBenefitsLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_bah_IncreaseDecreaseInPostemploymentBenefitsLiabilityNoncurrent_0373defb-2b6a-41ac-9cec-4254d0da8c2f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage_ead406b8-99db-4a56-b140-3661dd115cf4" xlink:href="bah-20210331.xsd#bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage_ead406b8-99db-4a56-b140-3661dd115cf4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_3b0c5dc3-7994-49f9-9a4a-ae2b776b4a70" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_3b0c5dc3-7994-49f9-9a4a-ae2b776b4a70" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_49b07128-c0d2-4f70-bee5-17b48756ee88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_49b07128-c0d2-4f70-bee5-17b48756ee88" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_272be944-41b6-4f8e-8089-c01c42f95a49" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_4435bb21-83e4-48cc-a87c-04d0483e92a0" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_272be944-41b6-4f8e-8089-c01c42f95a49" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameAxis_6e431d8d-5b2d-4722-b3e2-31e3b571d275" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_272be944-41b6-4f8e-8089-c01c42f95a49" xlink:to="loc_us-gaap_RetirementPlanNameAxis_6e431d8d-5b2d-4722-b3e2-31e3b571d275" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_6e431d8d-5b2d-4722-b3e2-31e3b571d275_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_6e431d8d-5b2d-4722-b3e2-31e3b571d275" xlink:to="loc_us-gaap_RetirementPlanNameDomain_6e431d8d-5b2d-4722-b3e2-31e3b571d275_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_56469581-171b-4312-8618-fb58779c4ca4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_6e431d8d-5b2d-4722-b3e2-31e3b571d275" xlink:to="loc_us-gaap_RetirementPlanNameDomain_56469581-171b-4312-8618-fb58779c4ca4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RetiredOfficersBonusPlanandRetiredVicePresidentBonusPlanMember_0d85aebf-d7df-442f-acf2-41d9a73d919f" xlink:href="bah-20210331.xsd#bah_RetiredOfficersBonusPlanandRetiredVicePresidentBonusPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_56469581-171b-4312-8618-fb58779c4ca4" xlink:to="loc_bah_RetiredOfficersBonusPlanandRetiredVicePresidentBonusPlanMember_0d85aebf-d7df-442f-acf2-41d9a73d919f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RetiredOfficersBonusPlanMember_13b3ccd2-5073-4600-a0fe-3d44388a6ac6" xlink:href="bah-20210331.xsd#bah_RetiredOfficersBonusPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_56469581-171b-4312-8618-fb58779c4ca4" xlink:to="loc_bah_RetiredOfficersBonusPlanMember_13b3ccd2-5073-4600-a0fe-3d44388a6ac6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RetiredVicePresidentsBonusPlanMember_d499ea91-fa39-4003-b1b0-faf7b45f6844" xlink:href="bah-20210331.xsd#bah_RetiredVicePresidentsBonusPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_56469581-171b-4312-8618-fb58779c4ca4" xlink:to="loc_bah_RetiredVicePresidentsBonusPlanMember_d499ea91-fa39-4003-b1b0-faf7b45f6844" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OfficerMedicalPlanMember_7ea7cfd0-1e4a-4c31-b31a-3c34e54bebc6" xlink:href="bah-20210331.xsd#bah_OfficerMedicalPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_56469581-171b-4312-8618-fb58779c4ca4" xlink:to="loc_bah_OfficerMedicalPlanMember_7ea7cfd0-1e4a-4c31-b31a-3c34e54bebc6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_721721e8-de4a-43d1-88a7-5cb3d2e3d8f2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_272be944-41b6-4f8e-8089-c01c42f95a49" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_721721e8-de4a-43d1-88a7-5cb3d2e3d8f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_721721e8-de4a-43d1-88a7-5cb3d2e3d8f2_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_721721e8-de4a-43d1-88a7-5cb3d2e3d8f2" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_721721e8-de4a-43d1-88a7-5cb3d2e3d8f2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_3414b9b6-3545-422c-951a-e3147a7dd20d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_721721e8-de4a-43d1-88a7-5cb3d2e3d8f2" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_3414b9b6-3545-422c-951a-e3147a7dd20d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_6e622dc3-4a58-44a8-b4d0-669daf669bd6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_3414b9b6-3545-422c-951a-e3147a7dd20d" xlink:to="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_6e622dc3-4a58-44a8-b4d0-669daf669bd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_4d4ea2d0-533d-4b63-81b2-79457622143b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_3414b9b6-3545-422c-951a-e3147a7dd20d" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_4d4ea2d0-533d-4b63-81b2-79457622143b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_056ab0ac-c4e6-4b4d-9c6c-329f1fe0eb0c" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_272be944-41b6-4f8e-8089-c01c42f95a49" xlink:to="loc_srt_TitleOfIndividualAxis_056ab0ac-c4e6-4b4d-9c6c-329f1fe0eb0c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_056ab0ac-c4e6-4b4d-9c6c-329f1fe0eb0c_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_056ab0ac-c4e6-4b4d-9c6c-329f1fe0eb0c" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_056ab0ac-c4e6-4b4d-9c6c-329f1fe0eb0c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_2d36f9f2-d0bc-46af-a792-8e17d5704979" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_056ab0ac-c4e6-4b4d-9c6c-329f1fe0eb0c" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_2d36f9f2-d0bc-46af-a792-8e17d5704979" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficerMember_45f4e2b9-3302-4aa9-b8b3-d960615427c2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_2d36f9f2-d0bc-46af-a792-8e17d5704979" xlink:to="loc_srt_OfficerMember_45f4e2b9-3302-4aa9-b8b3-d960615427c2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansComponentsofNetPostretirementMedicalExpenseDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#EmployeeBenefitPlansComponentsofNetPostretirementMedicalExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansComponentsofNetPostretirementMedicalExpenseDetails" xlink:type="extended" id="ia78bfdb248c44656a55f5e8d3a638835_EmployeeBenefitPlansComponentsofNetPostretirementMedicalExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_948f7d01-171b-47cd-82dd-b2e7c133e897" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_30141032-9413-4404-a8b0-aee26d8ee7b7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_948f7d01-171b-47cd-82dd-b2e7c133e897" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_30141032-9413-4404-a8b0-aee26d8ee7b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_3f0d80f6-552c-48c4-b6b8-2058955cac89" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_948f7d01-171b-47cd-82dd-b2e7c133e897" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_3f0d80f6-552c-48c4-b6b8-2058955cac89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_433914bd-0b9a-40cc-87bd-93e14f2d0469" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_948f7d01-171b-47cd-82dd-b2e7c133e897" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_433914bd-0b9a-40cc-87bd-93e14f2d0469" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_cb86173f-90b2-433d-aefe-2bb53d3ed70d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_948f7d01-171b-47cd-82dd-b2e7c133e897" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_cb86173f-90b2-433d-aefe-2bb53d3ed70d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_452682be-9c24-472a-8742-dfe2401eef9e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_948f7d01-171b-47cd-82dd-b2e7c133e897" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_452682be-9c24-472a-8742-dfe2401eef9e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameAxis_c2a3ffa3-a29b-49cc-9582-1a36c6d7684c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_452682be-9c24-472a-8742-dfe2401eef9e" xlink:to="loc_us-gaap_RetirementPlanNameAxis_c2a3ffa3-a29b-49cc-9582-1a36c6d7684c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_c2a3ffa3-a29b-49cc-9582-1a36c6d7684c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_c2a3ffa3-a29b-49cc-9582-1a36c6d7684c" xlink:to="loc_us-gaap_RetirementPlanNameDomain_c2a3ffa3-a29b-49cc-9582-1a36c6d7684c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_15779f3e-d971-4016-be9f-6428b5bcdcb4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_c2a3ffa3-a29b-49cc-9582-1a36c6d7684c" xlink:to="loc_us-gaap_RetirementPlanNameDomain_15779f3e-d971-4016-be9f-6428b5bcdcb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OfficerMedicalPlanMember_97c61925-3fda-4e86-85d9-293e7ba8b5fc" xlink:href="bah-20210331.xsd#bah_OfficerMedicalPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_15779f3e-d971-4016-be9f-6428b5bcdcb4" xlink:to="loc_bah_OfficerMedicalPlanMember_97c61925-3fda-4e86-85d9-293e7ba8b5fc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_8b8b4f06-f633-4749-8349-043826b5ad7e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_452682be-9c24-472a-8742-dfe2401eef9e" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_8b8b4f06-f633-4749-8349-043826b5ad7e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_8b8b4f06-f633-4749-8349-043826b5ad7e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_8b8b4f06-f633-4749-8349-043826b5ad7e" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_8b8b4f06-f633-4749-8349-043826b5ad7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_d279a271-1c82-4eb7-8070-12e51e15cdb7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_8b8b4f06-f633-4749-8349-043826b5ad7e" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_d279a271-1c82-4eb7-8070-12e51e15cdb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_a63e8885-6d8e-4b3c-aab9-c7018edb3530" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_d279a271-1c82-4eb7-8070-12e51e15cdb7" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_a63e8885-6d8e-4b3c-aab9-c7018edb3530" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansHealthcareCostTrendRatesDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#EmployeeBenefitPlansHealthcareCostTrendRatesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansHealthcareCostTrendRatesDetails" xlink:type="extended" id="i94f2b67cb11a4644ae3737d1e6f398aa_EmployeeBenefitPlansHealthcareCostTrendRatesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2b99d115-b80b-49ef-bb9e-1ea60c407b11" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPre65_2b8ad1b2-7895-4c2e-ad14-5e1d03f100e0" xlink:href="bah-20210331.xsd#bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPre65"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2b99d115-b80b-49ef-bb9e-1ea60c407b11" xlink:to="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPre65_2b8ad1b2-7895-4c2e-ad14-5e1d03f100e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePre65_cf878c7a-f118-477a-ac92-a844dc96c109" xlink:href="bah-20210331.xsd#bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePre65"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2b99d115-b80b-49ef-bb9e-1ea60c407b11" xlink:to="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePre65_cf878c7a-f118-477a-ac92-a844dc96c109" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPost65_f4a753ce-fbd1-427f-a5dd-103df0220c26" xlink:href="bah-20210331.xsd#bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPost65"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2b99d115-b80b-49ef-bb9e-1ea60c407b11" xlink:to="loc_bah_DefinedBenefitPlanHealthCareCostTrendRateAssumedForNextFiscalYearPost65_f4a753ce-fbd1-427f-a5dd-103df0220c26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePost65_02738a48-4ead-4a52-b47f-1a485123f118" xlink:href="bah-20210331.xsd#bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePost65"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2b99d115-b80b-49ef-bb9e-1ea60c407b11" xlink:to="loc_bah_DefinedBenefitPlanUltimateHealthCareCostTrendRatePost65_02738a48-4ead-4a52-b47f-1a485123f118" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_81556ffd-a8ac-43ea-8d12-d838bed68dfc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2b99d115-b80b-49ef-bb9e-1ea60c407b11" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_81556ffd-a8ac-43ea-8d12-d838bed68dfc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameAxis_a9796c69-7eb4-4a20-ac80-2e35f74839e5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_81556ffd-a8ac-43ea-8d12-d838bed68dfc" xlink:to="loc_us-gaap_RetirementPlanNameAxis_a9796c69-7eb4-4a20-ac80-2e35f74839e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_a9796c69-7eb4-4a20-ac80-2e35f74839e5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_a9796c69-7eb4-4a20-ac80-2e35f74839e5" xlink:to="loc_us-gaap_RetirementPlanNameDomain_a9796c69-7eb4-4a20-ac80-2e35f74839e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_62572abe-4d90-4b75-91bf-6d4c7470bfa6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_a9796c69-7eb4-4a20-ac80-2e35f74839e5" xlink:to="loc_us-gaap_RetirementPlanNameDomain_62572abe-4d90-4b75-91bf-6d4c7470bfa6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OfficerMedicalPlanMember_059a4c24-5181-4185-887a-dee6ba937998" xlink:href="bah-20210331.xsd#bah_OfficerMedicalPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_62572abe-4d90-4b75-91bf-6d4c7470bfa6" xlink:to="loc_bah_OfficerMedicalPlanMember_059a4c24-5181-4185-887a-dee6ba937998" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_9ebc5ba5-3c94-4273-8244-23dd521baa75" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_81556ffd-a8ac-43ea-8d12-d838bed68dfc" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_9ebc5ba5-3c94-4273-8244-23dd521baa75" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_9ebc5ba5-3c94-4273-8244-23dd521baa75_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9ebc5ba5-3c94-4273-8244-23dd521baa75" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_9ebc5ba5-3c94-4273-8244-23dd521baa75_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e9a5d8b3-4b36-4476-ba6f-422501a7e604" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9ebc5ba5-3c94-4273-8244-23dd521baa75" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e9a5d8b3-4b36-4476-ba6f-422501a7e604" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_b4a9f2bf-6dd0-46cc-9576-460f7b486d60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_e9a5d8b3-4b36-4476-ba6f-422501a7e604" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_b4a9f2bf-6dd0-46cc-9576-460f7b486d60" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansChangeinBenefitObligationandChangeinPlanAssetsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#EmployeeBenefitPlansChangeinBenefitObligationandChangeinPlanAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansChangeinBenefitObligationandChangeinPlanAssetsDetails" xlink:type="extended" id="i9000fae3412741b3a568bb4ce2e76300_EmployeeBenefitPlansChangeinBenefitObligationandChangeinPlanAssetsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39c988ed-8100-47f0-bbfe-62ff7cbf0d24" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39c988ed-8100-47f0-bbfe-62ff7cbf0d24" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_eb9b24e0-a60a-4119-a199-f16922510a0f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_eb9b24e0-a60a-4119-a199-f16922510a0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_e1f98fa8-47c7-4049-a347-013936ef710a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_e1f98fa8-47c7-4049-a347-013936ef710a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_48647052-6461-4203-8171-f22d2b8b36d1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_48647052-6461-4203-8171-f22d2b8b36d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_b7da479d-37fe-405a-a5fe-4ec33e19bfb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_b7da479d-37fe-405a-a5fe-4ec33e19bfb6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_0ca02fba-d56f-43cd-a9fc-e66a4a2e55f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_96ff8340-63b2-4e02-91bf-0e8b9d640eb4" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_0ca02fba-d56f-43cd-a9fc-e66a4a2e55f4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_f80392aa-2f7d-4a33-ad36-852e23aa361f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_8a7de425-9b1e-4555-b69d-0def80f66403" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39c988ed-8100-47f0-bbfe-62ff7cbf0d24" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_8a7de425-9b1e-4555-b69d-0def80f66403" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_1e38ca05-f1c3-4e53-ab39-746237ed830c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_8a7de425-9b1e-4555-b69d-0def80f66403" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_1e38ca05-f1c3-4e53-ab39-746237ed830c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_897d670c-8b9b-46c5-b38b-5648f3037b3e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_8a7de425-9b1e-4555-b69d-0def80f66403" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_897d670c-8b9b-46c5-b38b-5648f3037b3e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_c8ed8fa5-1cca-49cf-a961-7250f7b406a3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_8a7de425-9b1e-4555-b69d-0def80f66403" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_c8ed8fa5-1cca-49cf-a961-7250f7b406a3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_3615a139-0c20-4b77-ab34-434852add493" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_8b929567-695d-4acc-91eb-f3269a39aef9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_39c988ed-8100-47f0-bbfe-62ff7cbf0d24" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_8b929567-695d-4acc-91eb-f3269a39aef9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameAxis_bb51c6cd-1782-4e06-9594-c48dc2f33979" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_8b929567-695d-4acc-91eb-f3269a39aef9" xlink:to="loc_us-gaap_RetirementPlanNameAxis_bb51c6cd-1782-4e06-9594-c48dc2f33979" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_bb51c6cd-1782-4e06-9594-c48dc2f33979_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_bb51c6cd-1782-4e06-9594-c48dc2f33979" xlink:to="loc_us-gaap_RetirementPlanNameDomain_bb51c6cd-1782-4e06-9594-c48dc2f33979_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_f9390660-95ea-4166-a19e-991ee025ca57" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_bb51c6cd-1782-4e06-9594-c48dc2f33979" xlink:to="loc_us-gaap_RetirementPlanNameDomain_f9390660-95ea-4166-a19e-991ee025ca57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OfficerMedicalPlanMember_6be24c9c-d393-4007-a297-feecd9cb9249" xlink:href="bah-20210331.xsd#bah_OfficerMedicalPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_f9390660-95ea-4166-a19e-991ee025ca57" xlink:to="loc_bah_OfficerMedicalPlanMember_6be24c9c-d393-4007-a297-feecd9cb9249" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_b4cae03f-d8d5-4ace-92c6-152904f7f72c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_8b929567-695d-4acc-91eb-f3269a39aef9" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_b4cae03f-d8d5-4ace-92c6-152904f7f72c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_b4cae03f-d8d5-4ace-92c6-152904f7f72c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_b4cae03f-d8d5-4ace-92c6-152904f7f72c" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_b4cae03f-d8d5-4ace-92c6-152904f7f72c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_2c41580c-e6be-4134-8e9f-70f85138ab15" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_b4cae03f-d8d5-4ace-92c6-152904f7f72c" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_2c41580c-e6be-4134-8e9f-70f85138ab15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_da4548fb-14c9-483c-addf-e5ad131c03bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_2c41580c-e6be-4134-8e9f-70f85138ab15" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_da4548fb-14c9-483c-addf-e5ad131c03bb" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansWeightedAverageDiscountRateDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#EmployeeBenefitPlansWeightedAverageDiscountRateDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansWeightedAverageDiscountRateDetails" xlink:type="extended" id="i425296ef5c1a47d1835368aab680cb67_EmployeeBenefitPlansWeightedAverageDiscountRateDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_24249a5e-8812-459c-b6cc-41080473dcb9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_7d9b1346-a4fa-4cef-b36f-f6dd1cb89ffa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_24249a5e-8812-459c-b6cc-41080473dcb9" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_7d9b1346-a4fa-4cef-b36f-f6dd1cb89ffa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_bbcfd116-8266-40db-b94e-da49edd61415" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_24249a5e-8812-459c-b6cc-41080473dcb9" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_bbcfd116-8266-40db-b94e-da49edd61415" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameAxis_8c82a4af-9b12-4c86-9c88-450af2233a28" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_bbcfd116-8266-40db-b94e-da49edd61415" xlink:to="loc_us-gaap_RetirementPlanNameAxis_8c82a4af-9b12-4c86-9c88-450af2233a28" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_8c82a4af-9b12-4c86-9c88-450af2233a28_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_8c82a4af-9b12-4c86-9c88-450af2233a28" xlink:to="loc_us-gaap_RetirementPlanNameDomain_8c82a4af-9b12-4c86-9c88-450af2233a28_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanNameDomain_449a933f-7832-4a10-bb9c-a5853bf29e03" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_8c82a4af-9b12-4c86-9c88-450af2233a28" xlink:to="loc_us-gaap_RetirementPlanNameDomain_449a933f-7832-4a10-bb9c-a5853bf29e03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RetiredOfficersBonusPlanMember_c5511408-5178-4f29-9485-9ec4f0823ac6" xlink:href="bah-20210331.xsd#bah_RetiredOfficersBonusPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_449a933f-7832-4a10-bb9c-a5853bf29e03" xlink:to="loc_bah_RetiredOfficersBonusPlanMember_c5511408-5178-4f29-9485-9ec4f0823ac6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_RetiredVicePresidentsBonusPlanMember_d0a9795e-0713-4169-bfb2-2b46635abe3f" xlink:href="bah-20210331.xsd#bah_RetiredVicePresidentsBonusPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_449a933f-7832-4a10-bb9c-a5853bf29e03" xlink:to="loc_bah_RetiredVicePresidentsBonusPlanMember_d0a9795e-0713-4169-bfb2-2b46635abe3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_e210c532-61a5-42ad-bee5-2728e74cd234" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_bbcfd116-8266-40db-b94e-da49edd61415" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_e210c532-61a5-42ad-bee5-2728e74cd234" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e210c532-61a5-42ad-bee5-2728e74cd234_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e210c532-61a5-42ad-bee5-2728e74cd234" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e210c532-61a5-42ad-bee5-2728e74cd234_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e6957e02-124b-4681-a352-0fd573632d72" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e210c532-61a5-42ad-bee5-2728e74cd234" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e6957e02-124b-4681-a352-0fd573632d72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_03f7fdaf-9a38-471f-893e-656619e2db26" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_e6957e02-124b-4681-a352-0fd573632d72" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_03f7fdaf-9a38-471f-893e-656619e2db26" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleofChangesinAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#AccumulatedOtherComprehensiveLossScheduleofChangesinAccumulatedOtherComprehensiveIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleofChangesinAccumulatedOtherComprehensiveIncomeLossDetails" xlink:type="extended" id="if5d5848473b543478b4fe94f7d807581_AccumulatedOtherComprehensiveLossScheduleofChangesinAccumulatedOtherComprehensiveIncomeLossDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_108feaa7-7cec-46ce-a74f-f52dba8766f7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_5f5e74e3-8318-4247-9576-70ff9e9f329c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_108feaa7-7cec-46ce-a74f-f52dba8766f7" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_5f5e74e3-8318-4247-9576-70ff9e9f329c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_3c4fb06f-be83-4811-82ba-04900edc7418" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_5f5e74e3-8318-4247-9576-70ff9e9f329c" xlink:to="loc_us-gaap_StockholdersEquity_3c4fb06f-be83-4811-82ba-04900edc7418" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_37a46d87-6e97-4116-a72d-7b2e3d3bd8bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_5f5e74e3-8318-4247-9576-70ff9e9f329c" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_37a46d87-6e97-4116-a72d-7b2e3d3bd8bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_3c3ef8c1-71e2-49ba-99c4-f5707fd1ed24" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_5f5e74e3-8318-4247-9576-70ff9e9f329c" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_3c3ef8c1-71e2-49ba-99c4-f5707fd1ed24" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_2e4de1e1-eaf1-4269-9c97-53d846d2d658" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_5f5e74e3-8318-4247-9576-70ff9e9f329c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_2e4de1e1-eaf1-4269-9c97-53d846d2d658" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_17d892ed-b3d3-48f1-88da-f3d63ae9ed80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_f7676589-222a-4257-b764-bbd41ac8b149" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_108feaa7-7cec-46ce-a74f-f52dba8766f7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_f7676589-222a-4257-b764-bbd41ac8b149" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_732805db-061d-49b3-93cf-66e1498364c1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_108feaa7-7cec-46ce-a74f-f52dba8766f7" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_732805db-061d-49b3-93cf-66e1498364c1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_5a9434cc-c9a5-472e-8f20-49cca544223d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_732805db-061d-49b3-93cf-66e1498364c1" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_5a9434cc-c9a5-472e-8f20-49cca544223d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_5a9434cc-c9a5-472e-8f20-49cca544223d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5a9434cc-c9a5-472e-8f20-49cca544223d" xlink:to="loc_us-gaap_EquityComponentDomain_5a9434cc-c9a5-472e-8f20-49cca544223d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_c63cbfcb-f258-4965-b916-1995178b85f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5a9434cc-c9a5-472e-8f20-49cca544223d" xlink:to="loc_us-gaap_EquityComponentDomain_c63cbfcb-f258-4965-b916-1995178b85f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_15aa25f8-997e-4039-b791-fa36d51fcf88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c63cbfcb-f258-4965-b916-1995178b85f1" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_15aa25f8-997e-4039-b791-fa36d51fcf88" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_dbdb3a8e-bd64-483e-a099-376833d8cd5b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c63cbfcb-f258-4965-b916-1995178b85f1" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_dbdb3a8e-bd64-483e-a099-376833d8cd5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_dce05e10-c1ec-4498-85af-e512999c4f94" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_c63cbfcb-f258-4965-b916-1995178b85f1" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_dce05e10-c1ec-4498-85af-e512999c4f94" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleofReclassificationsoutofAccumulatedOtherComprehensiveLosstoNetIncomeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#AccumulatedOtherComprehensiveLossScheduleofReclassificationsoutofAccumulatedOtherComprehensiveLosstoNetIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleofReclassificationsoutofAccumulatedOtherComprehensiveLosstoNetIncomeDetails" xlink:type="extended" id="iad34d8cb83454e00a3df7fc601a2926c_AccumulatedOtherComprehensiveLossScheduleofReclassificationsoutofAccumulatedOtherComprehensiveLosstoNetIncomeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_91a47e01-048d-4207-90a3-6ba580208ae6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_de3e9247-7fc1-4419-b88b-18f0446dd6ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_91a47e01-048d-4207-90a3-6ba580208ae6" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_de3e9247-7fc1-4419-b88b-18f0446dd6ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_d20712c5-91c7-4adc-ac50-387a6014efa3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_91a47e01-048d-4207-90a3-6ba580208ae6" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_d20712c5-91c7-4adc-ac50-387a6014efa3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_73eac49a-2cbc-41f0-b0b2-21e4c67196e9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_91a47e01-048d-4207-90a3-6ba580208ae6" xlink:to="loc_us-gaap_NetIncomeLoss_73eac49a-2cbc-41f0-b0b2-21e4c67196e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_a6326d08-e6d1-4f55-9e2b-1b300d74b04f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_91a47e01-048d-4207-90a3-6ba580208ae6" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_a6326d08-e6d1-4f55-9e2b-1b300d74b04f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_ce7c9020-1f92-439e-92f7-404241da48a8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_a6326d08-e6d1-4f55-9e2b-1b300d74b04f" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_ce7c9020-1f92-439e-92f7-404241da48a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ce7c9020-1f92-439e-92f7-404241da48a8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_ce7c9020-1f92-439e-92f7-404241da48a8" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ce7c9020-1f92-439e-92f7-404241da48a8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_491c421f-631c-4589-963c-82c45cb2af30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_ce7c9020-1f92-439e-92f7-404241da48a8" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_491c421f-631c-4589-963c-82c45cb2af30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_fd16c1bb-5fc6-45e5-9370-cf46dbfbdc31" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_491c421f-631c-4589-963c-82c45cb2af30" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_fd16c1bb-5fc6-45e5-9370-cf46dbfbdc31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_3ac2baff-62b2-4784-858d-9284a959a6ff" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_a6326d08-e6d1-4f55-9e2b-1b300d74b04f" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_3ac2baff-62b2-4784-858d-9284a959a6ff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_3ac2baff-62b2-4784-858d-9284a959a6ff_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3ac2baff-62b2-4784-858d-9284a959a6ff" xlink:to="loc_us-gaap_EquityComponentDomain_3ac2baff-62b2-4784-858d-9284a959a6ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_1a9c6faf-92bd-4a14-9c94-89ad23be66df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_3ac2baff-62b2-4784-858d-9284a959a6ff" xlink:to="loc_us-gaap_EquityComponentDomain_1a9c6faf-92bd-4a14-9c94-89ad23be66df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_3782a48c-ae1e-4bc9-890f-32b17ddbee50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1a9c6faf-92bd-4a14-9c94-89ad23be66df" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_3782a48c-ae1e-4bc9-890f-32b17ddbee50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_8c7c8dbe-71db-46e8-ae84-d4ebd14fa5ab" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_1a9c6faf-92bd-4a14-9c94-89ad23be66df" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_8c7c8dbe-71db-46e8-ae84-d4ebd14fa5ab" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilitiesDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#OtherLongTermLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilitiesDetails" xlink:type="extended" id="i59c7d83debbe45308bc4ddc51446057f_OtherLongTermLiabilitiesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent_19ebbca9-5f7e-4061-8a86-e1dd66c0e803" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent_19ebbca9-5f7e-4061-8a86-e1dd66c0e803" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_2c195bc1-cc59-4d08-8994-09b829b901b1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_2c195bc1-cc59-4d08-8994-09b829b901b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesAndDeferredRevenueNoncurrent_c56ece78-9cfa-4b3f-83f8-391e45875e4a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesAndDeferredRevenueNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_OtherLiabilitiesAndDeferredRevenueNoncurrent_c56ece78-9cfa-4b3f-83f8-391e45875e4a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_8fd111eb-b5b5-4872-8e1b-7045ed6d8aa2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_OtherLiabilitiesNoncurrent_8fd111eb-b5b5-4872-8e1b-7045ed6d8aa2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_3d212817-49f6-4a95-af07-4e753c0aa423" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_3d212817-49f6-4a95-af07-4e753c0aa423" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_92052541-82d5-41a9-92c5-391c988f5f4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_92052541-82d5-41a9-92c5-391c988f5f4c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_fd1317a1-f20c-4da2-bdb3-a424c2ff8444" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PostemploymentBenefitsLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_fd1317a1-f20c-4da2-bdb3-a424c2ff8444" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_fd525687-ba0f-43a9-85f1-4548a9a88e20" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_78056011-71d8-4d4e-8312-247d35f11904" xlink:to="loc_us-gaap_OtherCommitmentsTable_fd525687-ba0f-43a9-85f1-4548a9a88e20" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_6c7b3ef8-8109-4f5c-80aa-f8b2b821730e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_fd525687-ba0f-43a9-85f1-4548a9a88e20" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_6c7b3ef8-8109-4f5c-80aa-f8b2b821730e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_6c7b3ef8-8109-4f5c-80aa-f8b2b821730e_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_6c7b3ef8-8109-4f5c-80aa-f8b2b821730e" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_6c7b3ef8-8109-4f5c-80aa-f8b2b821730e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_3eedb080-a903-44e3-9448-7ecb6f0f13ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_6c7b3ef8-8109-4f5c-80aa-f8b2b821730e" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_3eedb080-a903-44e3-9448-7ecb6f0f13ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_aab5ea28-53b4-468f-a7d5-c0487649f26f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_3eedb080-a903-44e3-9448-7ecb6f0f13ae" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_aab5ea28-53b4-468f-a7d5-c0487649f26f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_39fff70e-431e-42f9-b26a-3570681f5c2c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_fd525687-ba0f-43a9-85f1-4548a9a88e20" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_39fff70e-431e-42f9-b26a-3570681f5c2c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_39fff70e-431e-42f9-b26a-3570681f5c2c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_39fff70e-431e-42f9-b26a-3570681f5c2c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_39fff70e-431e-42f9-b26a-3570681f5c2c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b1e2eb64-cd27-4e25-96e1-4cbd305edbc0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_39fff70e-431e-42f9-b26a-3570681f5c2c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b1e2eb64-cd27-4e25-96e1-4cbd305edbc0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_6b754fb5-fc98-466a-b35b-f3df7748f688" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b1e2eb64-cd27-4e25-96e1-4cbd305edbc0" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_6b754fb5-fc98-466a-b35b-f3df7748f688" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_58bae491-f292-48ef-bb9e-510957545d8d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_fd525687-ba0f-43a9-85f1-4548a9a88e20" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_58bae491-f292-48ef-bb9e-510957545d8d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_58bae491-f292-48ef-bb9e-510957545d8d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_58bae491-f292-48ef-bb9e-510957545d8d" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_58bae491-f292-48ef-bb9e-510957545d8d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_d8be93ea-8efc-4b0a-8bd3-2445d8fe7e63" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_58bae491-f292-48ef-bb9e-510957545d8d" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_d8be93ea-8efc-4b0a-8bd3-2445d8fe7e63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_7fd7da23-dec5-4c4d-b8fd-7266ff9a3aac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_d8be93ea-8efc-4b0a-8bd3-2445d8fe7e63" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_7fd7da23-dec5-4c4d-b8fd-7266ff9a3aac" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockholdersEquityNarrativeDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockholdersEquityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockholdersEquityNarrativeDetails" xlink:type="extended" id="i9d07ec23cc0f421abf4123a297e863a7_StockholdersEquityNarrativeDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ed81e240-cf26-4fb6-896d-10af16bce31c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_CommonStockVotesPerShare_366e4083-d091-4f25-8e57-8ffdd487db3c" xlink:href="bah-20210331.xsd#bah_CommonStockVotesPerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ed81e240-cf26-4fb6-896d-10af16bce31c" xlink:to="loc_bah_CommonStockVotesPerShare_366e4083-d091-4f25-8e57-8ffdd487db3c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_2c328c45-bfe9-4433-997c-7e935e45a663" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ed81e240-cf26-4fb6-896d-10af16bce31c" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_2c328c45-bfe9-4433-997c-7e935e45a663" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_80896d04-0981-46ad-8d4b-afdbcdbab2ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ed81e240-cf26-4fb6-896d-10af16bce31c" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_80896d04-0981-46ad-8d4b-afdbcdbab2ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_1bc8ee1b-03c9-4dea-bcd9-9eead455d7aa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ed81e240-cf26-4fb6-896d-10af16bce31c" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_1bc8ee1b-03c9-4dea-bcd9-9eead455d7aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_774295c9-7a9f-4f85-8a16-839c79ad0f38" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ed81e240-cf26-4fb6-896d-10af16bce31c" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_774295c9-7a9f-4f85-8a16-839c79ad0f38" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_4d24abb3-9a64-4528-95d3-fac232818ff8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_774295c9-7a9f-4f85-8a16-839c79ad0f38" xlink:to="loc_us-gaap_StatementClassOfStockAxis_4d24abb3-9a64-4528-95d3-fac232818ff8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4d24abb3-9a64-4528-95d3-fac232818ff8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4d24abb3-9a64-4528-95d3-fac232818ff8" xlink:to="loc_us-gaap_ClassOfStockDomain_4d24abb3-9a64-4528-95d3-fac232818ff8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_fc13c705-0ad5-4dbe-87c0-b38656b3e20d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4d24abb3-9a64-4528-95d3-fac232818ff8" xlink:to="loc_us-gaap_ClassOfStockDomain_fc13c705-0ad5-4dbe-87c0-b38656b3e20d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_ce33f668-452a-46d8-b2f4-0ea3b8d6032a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_fc13c705-0ad5-4dbe-87c0-b38656b3e20d" xlink:to="loc_us-gaap_CommonClassAMember_ce33f668-452a-46d8-b2f4-0ea3b8d6032a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockholdersEquitySummaryofDividendsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockholdersEquitySummaryofDividendsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockholdersEquitySummaryofDividendsDetails" xlink:type="extended" id="iddd471d40bde4b92901326141aca6fa7_StockholdersEquitySummaryofDividendsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5c0e2847-b5b7-400a-8cbf-bd0d0e4c4fd1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_3fc707c2-486c-4662-aee1-78030ef912bd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5c0e2847-b5b7-400a-8cbf-bd0d0e4c4fd1" xlink:to="loc_us-gaap_DividendsCommonStock_3fc707c2-486c-4662-aee1-78030ef912bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_2308ea9d-73f9-4bde-b313-77ac4cbdba30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5c0e2847-b5b7-400a-8cbf-bd0d0e4c4fd1" xlink:to="loc_us-gaap_Dividends_2308ea9d-73f9-4bde-b313-77ac4cbdba30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6a9f995-7a3a-409f-b2f4-b5b6d3a63bb1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_5c0e2847-b5b7-400a-8cbf-bd0d0e4c4fd1" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6a9f995-7a3a-409f-b2f4-b5b6d3a63bb1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeAxis_7506cb1f-4861-450a-b3fa-7b971f5632e6" xlink:href="bah-20210331.xsd#bah_DividendTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6a9f995-7a3a-409f-b2f4-b5b6d3a63bb1" xlink:to="loc_bah_DividendTypeAxis_7506cb1f-4861-450a-b3fa-7b971f5632e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeDomain_7506cb1f-4861-450a-b3fa-7b971f5632e6_default" xlink:href="bah-20210331.xsd#bah_DividendTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_DividendTypeAxis_7506cb1f-4861-450a-b3fa-7b971f5632e6" xlink:to="loc_bah_DividendTypeDomain_7506cb1f-4861-450a-b3fa-7b971f5632e6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeDomain_ad38d9bf-f2d1-47a4-af54-d1af5825aba7" xlink:href="bah-20210331.xsd#bah_DividendTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_DividendTypeAxis_7506cb1f-4861-450a-b3fa-7b971f5632e6" xlink:to="loc_bah_DividendTypeDomain_ad38d9bf-f2d1-47a4-af54-d1af5825aba7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendequivalentMember_61551d64-a3cb-48d5-9686-2e878c42cba6" xlink:href="bah-20210331.xsd#bah_DividendequivalentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_ad38d9bf-f2d1-47a4-af54-d1af5825aba7" xlink:to="loc_bah_DividendequivalentMember_61551d64-a3cb-48d5-9686-2e878c42cba6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockBasedCompensationStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockbasedCompensationExpenseDetails" xlink:type="extended" id="id5e830e45863410c871c6218e011e455_StockBasedCompensationStockbasedCompensationExpenseDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_73f2e71e-c247-468a-a516-b72d5faff94d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_e32fd202-af76-410c-8383-0b2b213feaa3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_73f2e71e-c247-468a-a516-b72d5faff94d" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_e32fd202-af76-410c-8383-0b2b213feaa3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_6b9eb650-5688-4f03-9cd0-72299c83edb4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_73f2e71e-c247-468a-a516-b72d5faff94d" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_6b9eb650-5688-4f03-9cd0-72299c83edb4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_099ea1f2-86a1-4fb4-92cf-6b920464c802" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_6b9eb650-5688-4f03-9cd0-72299c83edb4" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_099ea1f2-86a1-4fb4-92cf-6b920464c802" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_099ea1f2-86a1-4fb4-92cf-6b920464c802_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_099ea1f2-86a1-4fb4-92cf-6b920464c802" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_099ea1f2-86a1-4fb4-92cf-6b920464c802_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_44dfe899-ef9a-4b58-a981-ad9ccf99f992" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_099ea1f2-86a1-4fb4-92cf-6b920464c802" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_44dfe899-ef9a-4b58-a981-ad9ccf99f992" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_04154c58-d327-4614-96c7-5abcbe25029b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_44dfe899-ef9a-4b58-a981-ad9ccf99f992" xlink:to="loc_us-gaap_CostOfSalesMember_04154c58-d327-4614-96c7-5abcbe25029b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_739aa8c4-d4bf-435b-9f76-9acf412cd242" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_44dfe899-ef9a-4b58-a981-ad9ccf99f992" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_739aa8c4-d4bf-435b-9f76-9acf412cd242" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_a20e99d0-1368-4944-b0c0-58dad441f352" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_6b9eb650-5688-4f03-9cd0-72299c83edb4" xlink:to="loc_us-gaap_PlanNameAxis_a20e99d0-1368-4944-b0c0-58dad441f352" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_a20e99d0-1368-4944-b0c0-58dad441f352_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_a20e99d0-1368-4944-b0c0-58dad441f352" xlink:to="loc_us-gaap_PlanNameDomain_a20e99d0-1368-4944-b0c0-58dad441f352_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_3d2150fb-8e8a-4b90-899e-28bf7c93d77c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_a20e99d0-1368-4944-b0c0-58dad441f352" xlink:to="loc_us-gaap_PlanNameDomain_3d2150fb-8e8a-4b90-899e-28bf7c93d77c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_0b4a3658-a086-46c2-9623-de4158c09ce2" xlink:href="bah-20210331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_3d2150fb-8e8a-4b90-899e-28bf7c93d77c" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_0b4a3658-a086-46c2-9623-de4158c09ce2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AnnualIncentivePlanMember_2f6725a5-dd17-409e-8453-7bbacda3c874" xlink:href="bah-20210331.xsd#bah_AnnualIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_3d2150fb-8e8a-4b90-899e-28bf7c93d77c" xlink:to="loc_bah_AnnualIncentivePlanMember_2f6725a5-dd17-409e-8453-7bbacda3c874" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0b3a012e-5dcd-4410-9890-55070777d386" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_6b9eb650-5688-4f03-9cd0-72299c83edb4" xlink:to="loc_us-gaap_AwardTypeAxis_0b3a012e-5dcd-4410-9890-55070777d386" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b3a012e-5dcd-4410-9890-55070777d386_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0b3a012e-5dcd-4410-9890-55070777d386" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0b3a012e-5dcd-4410-9890-55070777d386_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1aa70e-9dc6-43b8-bd85-fb5340e974da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0b3a012e-5dcd-4410-9890-55070777d386" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1aa70e-9dc6-43b8-bd85-fb5340e974da" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_381970c3-831a-4a0b-8566-7f6a1d24267a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1aa70e-9dc6-43b8-bd85-fb5340e974da" xlink:to="loc_us-gaap_EmployeeStockOptionMember_381970c3-831a-4a0b-8566-7f6a1d24267a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_fea8218c-230f-4e08-8ecb-4d88aaf26c30" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6a1aa70e-9dc6-43b8-bd85-fb5340e974da" xlink:to="loc_us-gaap_RestrictedStockMember_fea8218c-230f-4e08-8ecb-4d88aaf26c30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_3e9ff34c-62e7-43e0-9296-790e99fc38a5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_6b9eb650-5688-4f03-9cd0-72299c83edb4" xlink:to="loc_us-gaap_StatementClassOfStockAxis_3e9ff34c-62e7-43e0-9296-790e99fc38a5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_3e9ff34c-62e7-43e0-9296-790e99fc38a5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3e9ff34c-62e7-43e0-9296-790e99fc38a5" xlink:to="loc_us-gaap_ClassOfStockDomain_3e9ff34c-62e7-43e0-9296-790e99fc38a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4fd4b2b1-4070-4d6b-a133-ed527f035098" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_3e9ff34c-62e7-43e0-9296-790e99fc38a5" xlink:to="loc_us-gaap_ClassOfStockDomain_4fd4b2b1-4070-4d6b-a133-ed527f035098" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_d01976af-c3d3-48b7-b5df-c035c378ac40" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_4fd4b2b1-4070-4d6b-a133-ed527f035098" xlink:to="loc_us-gaap_CommonClassAMember_d01976af-c3d3-48b7-b5df-c035c378ac40" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationSummaryofUnrecognizedCompensationDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockBasedCompensationSummaryofUnrecognizedCompensationDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationSummaryofUnrecognizedCompensationDetails" xlink:type="extended" id="ia3793de13e5146ecb06b8d0428e91d20_StockBasedCompensationSummaryofUnrecognizedCompensationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_7c36ffc8-9632-448b-aa1c-4ba83e5135b6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_7c36ffc8-9632-448b-aa1c-4ba83e5135b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_540a52ee-4d0a-4903-88a1-7b8bccc36057" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_540a52ee-4d0a-4903-88a1-7b8bccc36057" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_46e7e907-4ad6-42dd-a0bb-fdbf26758fd2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedCompensationCostNext12Months_b5f98670-1ba5-4e3e-aa8d-2398c07302b4" xlink:href="bah-20210331.xsd#bah_UnrecognizedCompensationCostNext12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_bah_UnrecognizedCompensationCostNext12Months_b5f98670-1ba5-4e3e-aa8d-2398c07302b4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedCompensationCostYearTwo_5643328a-5770-43ab-acb7-bfe4af0818bd" xlink:href="bah-20210331.xsd#bah_UnrecognizedCompensationCostYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_bah_UnrecognizedCompensationCostYearTwo_5643328a-5770-43ab-acb7-bfe4af0818bd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedCompensationCostYearThree_33a7fc76-649b-4d00-a8b7-b73e3ae6e763" xlink:href="bah-20210331.xsd#bah_UnrecognizedCompensationCostYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_bah_UnrecognizedCompensationCostYearThree_33a7fc76-649b-4d00-a8b7-b73e3ae6e763" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedCompensationCostYearFour_dda23081-1b58-4fbc-93f3-6785cc605c7f" xlink:href="bah-20210331.xsd#bah_UnrecognizedCompensationCostYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_bah_UnrecognizedCompensationCostYearFour_dda23081-1b58-4fbc-93f3-6785cc605c7f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_UnrecognizedCompensationCostYearFive_92bdd511-4aa6-4163-a2d1-f42544dca41a" xlink:href="bah-20210331.xsd#bah_UnrecognizedCompensationCostYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_bah_UnrecognizedCompensationCostYearFive_92bdd511-4aa6-4163-a2d1-f42544dca41a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ea409dd-00f2-4192-b5b2-cf52710fa070" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_66dada83-7c75-4178-b00a-2c32e9754607" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ea409dd-00f2-4192-b5b2-cf52710fa070" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_7dcef8ab-9a04-4167-86aa-d3b95656dc8b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ea409dd-00f2-4192-b5b2-cf52710fa070" xlink:to="loc_us-gaap_PlanNameAxis_7dcef8ab-9a04-4167-86aa-d3b95656dc8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_7dcef8ab-9a04-4167-86aa-d3b95656dc8b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_7dcef8ab-9a04-4167-86aa-d3b95656dc8b" xlink:to="loc_us-gaap_PlanNameDomain_7dcef8ab-9a04-4167-86aa-d3b95656dc8b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_5fdfd503-1c93-400a-8cd1-563929655b77" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_7dcef8ab-9a04-4167-86aa-d3b95656dc8b" xlink:to="loc_us-gaap_PlanNameDomain_5fdfd503-1c93-400a-8cd1-563929655b77" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_0856954e-bffb-421d-915e-7f80ee917fa9" xlink:href="bah-20210331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_5fdfd503-1c93-400a-8cd1-563929655b77" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_0856954e-bffb-421d-915e-7f80ee917fa9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AnnualIncentivePlanMember_a84c0903-a147-49a6-8603-ab046dcce63e" xlink:href="bah-20210331.xsd#bah_AnnualIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_5fdfd503-1c93-400a-8cd1-563929655b77" xlink:to="loc_bah_AnnualIncentivePlanMember_a84c0903-a147-49a6-8603-ab046dcce63e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_fd6510eb-2335-4c3c-832e-6fddaddec487" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ea409dd-00f2-4192-b5b2-cf52710fa070" xlink:to="loc_us-gaap_AwardTypeAxis_fd6510eb-2335-4c3c-832e-6fddaddec487" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fd6510eb-2335-4c3c-832e-6fddaddec487_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_fd6510eb-2335-4c3c-832e-6fddaddec487" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_fd6510eb-2335-4c3c-832e-6fddaddec487_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a8585162-bf32-4162-bb21-b80aaa89a7f1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_fd6510eb-2335-4c3c-832e-6fddaddec487" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a8585162-bf32-4162-bb21-b80aaa89a7f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_147ad1e0-1404-4e4d-93c7-110d42da5a2f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a8585162-bf32-4162-bb21-b80aaa89a7f1" xlink:to="loc_us-gaap_EmployeeStockOptionMember_147ad1e0-1404-4e4d-93c7-110d42da5a2f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_b460a189-e408-4780-ad92-0eb344e70cb9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a8585162-bf32-4162-bb21-b80aaa89a7f1" xlink:to="loc_us-gaap_RestrictedStockMember_b460a189-e408-4780-ad92-0eb344e70cb9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_99f2baf1-3fe3-4fa5-8d95-1c8b760a7e27" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_2ea409dd-00f2-4192-b5b2-cf52710fa070" xlink:to="loc_us-gaap_StatementClassOfStockAxis_99f2baf1-3fe3-4fa5-8d95-1c8b760a7e27" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_99f2baf1-3fe3-4fa5-8d95-1c8b760a7e27_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_99f2baf1-3fe3-4fa5-8d95-1c8b760a7e27" xlink:to="loc_us-gaap_ClassOfStockDomain_99f2baf1-3fe3-4fa5-8d95-1c8b760a7e27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_e9bc6171-902c-4ee3-807c-5be8ac353365" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_99f2baf1-3fe3-4fa5-8d95-1c8b760a7e27" xlink:to="loc_us-gaap_ClassOfStockDomain_e9bc6171-902c-4ee3-807c-5be8ac353365" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_dbd510e3-e3f2-498d-8f7f-fbf4450efedd" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_e9bc6171-902c-4ee3-807c-5be8ac353365" xlink:to="loc_us-gaap_CommonClassAMember_dbd510e3-e3f2-498d-8f7f-fbf4450efedd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationSummaryofStockPlansDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockBasedCompensationSummaryofStockPlansDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationSummaryofStockPlansDetails" xlink:type="extended" id="ic96152d53c4b475287c2f15f1f6c16b1_StockBasedCompensationSummaryofStockPlansDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_56f8d8e1-b445-4c33-8dd3-0336a4de4dfa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_56f8d8e1-b445-4c33-8dd3-0336a4de4dfa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_c141db24-7cf4-48e5-b112-f8b8f46ae05f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_c141db24-7cf4-48e5-b112-f8b8f46ae05f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e67af14c-598d-402a-9e79-41b01f1181eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e67af14c-598d-402a-9e79-41b01f1181eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_a8cb99c6-99a2-4e33-8ed1-710bdafbec6f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_a8cb99c6-99a2-4e33-8ed1-710bdafbec6f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_65499fdc-5537-4b4e-8b04-48155e7a957a" xlink:href="bah-20210331.xsd#bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_65499fdc-5537-4b4e-8b04-48155e7a957a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_1c544a74-f4f6-4308-9e65-8dd0fb9f4d64" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_1c544a74-f4f6-4308-9e65-8dd0fb9f4d64" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_b489ac1e-c085-4788-a4a0-81ca6284380d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_b489ac1e-c085-4788-a4a0-81ca6284380d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_42a16861-343b-491c-b85c-ef7cee55c274" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_42a16861-343b-491c-b85c-ef7cee55c274" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_193bdfd3-df71-4efe-9a2c-c5d53915626d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_193bdfd3-df71-4efe-9a2c-c5d53915626d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_ec406b9b-b85c-485a-be55-207e8215f336" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_SharePrice_ec406b9b-b85c-485a-be55-207e8215f336" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_5e48b553-856d-409c-9819-750e405acb9b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_5e48b553-856d-409c-9819-750e405acb9b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_a2f50f22-5ad3-4c6b-8e5a-7ffece98e26e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_a2f50f22-5ad3-4c6b-8e5a-7ffece98e26e" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_44baebbb-ceb8-450e-87fc-01d2fdcb30f6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_6b57846b-aa32-4242-aced-6f59c230088f" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:to="loc_srt_RangeAxis_6b57846b-aa32-4242-aced-6f59c230088f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_6b57846b-aa32-4242-aced-6f59c230088f_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6b57846b-aa32-4242-aced-6f59c230088f" xlink:to="loc_srt_RangeMember_6b57846b-aa32-4242-aced-6f59c230088f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f546720e-2ced-412f-82d9-730f277ec309" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6b57846b-aa32-4242-aced-6f59c230088f" xlink:to="loc_srt_RangeMember_f546720e-2ced-412f-82d9-730f277ec309" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_c493c9cb-7894-413f-af5f-e3f129cd6653" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f546720e-2ced-412f-82d9-730f277ec309" xlink:to="loc_srt_MinimumMember_c493c9cb-7894-413f-af5f-e3f129cd6653" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_600e0da3-b85d-420b-8195-c8a041b9f4e1" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f546720e-2ced-412f-82d9-730f277ec309" xlink:to="loc_srt_MaximumMember_600e0da3-b85d-420b-8195-c8a041b9f4e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_b3a9e240-f6a7-4fa4-a346-449cd2a43aeb" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:to="loc_srt_TitleOfIndividualAxis_b3a9e240-f6a7-4fa4-a346-449cd2a43aeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b3a9e240-f6a7-4fa4-a346-449cd2a43aeb_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_b3a9e240-f6a7-4fa4-a346-449cd2a43aeb" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_b3a9e240-f6a7-4fa4-a346-449cd2a43aeb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c3fa86f-3594-4a7c-91fc-2d2786ae3e51" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_b3a9e240-f6a7-4fa4-a346-449cd2a43aeb" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c3fa86f-3594-4a7c-91fc-2d2786ae3e51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OfficerMember_17151525-2925-40b2-a7b1-ed1255c4bfa4" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c3fa86f-3594-4a7c-91fc-2d2786ae3e51" xlink:to="loc_srt_OfficerMember_17151525-2925-40b2-a7b1-ed1255c4bfa4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_DirectorMember_2e2e238a-bd6c-4abc-a427-d54b80ea6b8a" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_DirectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_1c3fa86f-3594-4a7c-91fc-2d2786ae3e51" xlink:to="loc_srt_DirectorMember_2e2e238a-bd6c-4abc-a427-d54b80ea6b8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_6892552b-edfc-404e-aef0-a0a87462f9ef" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:to="loc_us-gaap_PlanNameAxis_6892552b-edfc-404e-aef0-a0a87462f9ef" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_6892552b-edfc-404e-aef0-a0a87462f9ef_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_6892552b-edfc-404e-aef0-a0a87462f9ef" xlink:to="loc_us-gaap_PlanNameDomain_6892552b-edfc-404e-aef0-a0a87462f9ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_b867626f-d611-41d1-ad24-96e7104e244a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_6892552b-edfc-404e-aef0-a0a87462f9ef" xlink:to="loc_us-gaap_PlanNameDomain_b867626f-d611-41d1-ad24-96e7104e244a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_08fb6244-d035-48f6-bf76-c574ca39090d" xlink:href="bah-20210331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b867626f-d611-41d1-ad24-96e7104e244a" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_08fb6244-d035-48f6-bf76-c574ca39090d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AnnualIncentivePlanMember_a501abd6-7c64-453e-bfd9-b7e6b9eb66ac" xlink:href="bah-20210331.xsd#bah_AnnualIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_b867626f-d611-41d1-ad24-96e7104e244a" xlink:to="loc_bah_AnnualIncentivePlanMember_a501abd6-7c64-453e-bfd9-b7e6b9eb66ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_1c1f8562-7ad7-4a1b-bbc0-bc019678e8ca" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:to="loc_us-gaap_AwardTypeAxis_1c1f8562-7ad7-4a1b-bbc0-bc019678e8ca" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1c1f8562-7ad7-4a1b-bbc0-bc019678e8ca_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_1c1f8562-7ad7-4a1b-bbc0-bc019678e8ca" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1c1f8562-7ad7-4a1b-bbc0-bc019678e8ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0c10b4d-f294-4761-abe6-e76f7d7bdc51" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_1c1f8562-7ad7-4a1b-bbc0-bc019678e8ca" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0c10b4d-f294-4761-abe6-e76f7d7bdc51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_a630c6e6-aa65-401c-8526-2a36aa6447b3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0c10b4d-f294-4761-abe6-e76f7d7bdc51" xlink:to="loc_us-gaap_EmployeeStockOptionMember_a630c6e6-aa65-401c-8526-2a36aa6447b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_b9cd5a2e-66cc-4e22-b927-5f515e695ea9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0c10b4d-f294-4761-abe6-e76f7d7bdc51" xlink:to="loc_us-gaap_RestrictedStockMember_b9cd5a2e-66cc-4e22-b927-5f515e695ea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_528a0eab-dbac-4673-9b56-0d9c3dd68f32" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e0c10b4d-f294-4761-abe6-e76f7d7bdc51" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_528a0eab-dbac-4673-9b56-0d9c3dd68f32" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_ed09d7f8-e936-4d28-bbef-9101df896964" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_6906691e-0002-4bd8-8586-9742b7ac172a" xlink:to="loc_us-gaap_StatementClassOfStockAxis_ed09d7f8-e936-4d28-bbef-9101df896964" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_ed09d7f8-e936-4d28-bbef-9101df896964_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_ed09d7f8-e936-4d28-bbef-9101df896964" xlink:to="loc_us-gaap_ClassOfStockDomain_ed09d7f8-e936-4d28-bbef-9101df896964_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_da21ece7-c57c-467f-a0a9-355588a6d424" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_ed09d7f8-e936-4d28-bbef-9101df896964" xlink:to="loc_us-gaap_ClassOfStockDomain_da21ece7-c57c-467f-a0a9-355588a6d424" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_0e524c3f-9287-461d-adaa-74259894a636" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_da21ece7-c57c-467f-a0a9-355588a6d424" xlink:to="loc_us-gaap_CommonClassAMember_0e524c3f-9287-461d-adaa-74259894a636" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockOptionAssumptionsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockBasedCompensationStockOptionAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockOptionAssumptionsDetails" xlink:type="extended" id="i2d19560b64a44416b8cd8bf5c3f484e0_StockBasedCompensationStockOptionAssumptionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_a9598e64-a411-4894-ae30-13245ef95c4e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_a9598e64-a411-4894-ae30-13245ef95c4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_18a87077-2c9d-4c6f-9348-6d866f2c079c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_18a87077-2c9d-4c6f-9348-6d866f2c079c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_a9be1aad-fa4e-4193-8fd4-cb3dde541a90" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_a9be1aad-fa4e-4193-8fd4-cb3dde541a90" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_3cef6bd9-f60f-4a7e-ab14-36d32e674341" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_3cef6bd9-f60f-4a7e-ab14-36d32e674341" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_bb124e58-8bf9-4c1b-9050-befe899b7c52" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_bb124e58-8bf9-4c1b-9050-befe899b7c52" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_16248bd7-848e-4f52-80a5-20cea67f76d0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_16248bd7-848e-4f52-80a5-20cea67f76d0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c4f3aead-b9ba-4e4f-a5eb-4ba013d5dc98" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_141bdad1-a9dc-46c6-b001-4e17d69d4dc2" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c4f3aead-b9ba-4e4f-a5eb-4ba013d5dc98" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeAxis_e19a94bb-e38f-4abd-b972-1141d87dd004" xlink:href="bah-20210331.xsd#bah_DividendTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c4f3aead-b9ba-4e4f-a5eb-4ba013d5dc98" xlink:to="loc_bah_DividendTypeAxis_e19a94bb-e38f-4abd-b972-1141d87dd004" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeDomain_e19a94bb-e38f-4abd-b972-1141d87dd004_default" xlink:href="bah-20210331.xsd#bah_DividendTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_DividendTypeAxis_e19a94bb-e38f-4abd-b972-1141d87dd004" xlink:to="loc_bah_DividendTypeDomain_e19a94bb-e38f-4abd-b972-1141d87dd004_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeDomain_3181b0ff-645a-4130-9b79-fc9c125305ed" xlink:href="bah-20210331.xsd#bah_DividendTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_DividendTypeAxis_e19a94bb-e38f-4abd-b972-1141d87dd004" xlink:to="loc_bah_DividendTypeDomain_3181b0ff-645a-4130-9b79-fc9c125305ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OrdinaryCashDividendMember_d58f5e74-4ae7-4890-ad63-92b6859075eb" xlink:href="bah-20210331.xsd#bah_OrdinaryCashDividendMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_3181b0ff-645a-4130-9b79-fc9c125305ed" xlink:to="loc_bah_OrdinaryCashDividendMember_d58f5e74-4ae7-4890-ad63-92b6859075eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_d9bce331-dd8b-4e8c-bedf-35ca62a5b67d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c4f3aead-b9ba-4e4f-a5eb-4ba013d5dc98" xlink:to="loc_us-gaap_AwardTypeAxis_d9bce331-dd8b-4e8c-bedf-35ca62a5b67d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d9bce331-dd8b-4e8c-bedf-35ca62a5b67d_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_d9bce331-dd8b-4e8c-bedf-35ca62a5b67d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d9bce331-dd8b-4e8c-bedf-35ca62a5b67d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0777088b-9720-4adc-862b-9e01c758c430" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_d9bce331-dd8b-4e8c-bedf-35ca62a5b67d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0777088b-9720-4adc-862b-9e01c758c430" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_e34444f3-8951-42f3-bbba-f61939310d25" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0777088b-9720-4adc-862b-9e01c758c430" xlink:to="loc_us-gaap_EmployeeStockOptionMember_e34444f3-8951-42f3-bbba-f61939310d25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7009a037-1846-4b98-b170-ee202cc3c689" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c4f3aead-b9ba-4e4f-a5eb-4ba013d5dc98" xlink:to="loc_srt_RangeAxis_7009a037-1846-4b98-b170-ee202cc3c689" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7009a037-1846-4b98-b170-ee202cc3c689_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_7009a037-1846-4b98-b170-ee202cc3c689" xlink:to="loc_srt_RangeMember_7009a037-1846-4b98-b170-ee202cc3c689_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ed6a14b1-549f-4286-8d84-a468898be479" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_7009a037-1846-4b98-b170-ee202cc3c689" xlink:to="loc_srt_RangeMember_ed6a14b1-549f-4286-8d84-a468898be479" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_0c7450fb-44bd-472a-ae51-8222d7424f58" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ed6a14b1-549f-4286-8d84-a468898be479" xlink:to="loc_srt_MinimumMember_0c7450fb-44bd-472a-ae51-8222d7424f58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_f6d6d3ed-e1a4-436a-924f-dfc1986cd033" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ed6a14b1-549f-4286-8d84-a468898be479" xlink:to="loc_srt_MaximumMember_f6d6d3ed-e1a4-436a-924f-dfc1986cd033" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockOptionandRestrictedStockAwardActivityDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockBasedCompensationStockOptionandRestrictedStockAwardActivityDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockOptionandRestrictedStockAwardActivityDetails" xlink:type="extended" id="i66f6eb11f9404bd188ae7b8696b37c91_StockBasedCompensationStockOptionandRestrictedStockAwardActivityDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_a97b37fd-5177-4605-b6a9-d30379b76b69" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_a97b37fd-5177-4605-b6a9-d30379b76b69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_ab85ef06-8507-43ef-bd4e-51a6035b572d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_a97b37fd-5177-4605-b6a9-d30379b76b69" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_ab85ef06-8507-43ef-bd4e-51a6035b572d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_00e8091a-dfad-4395-b3e6-757f67089f34" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_a97b37fd-5177-4605-b6a9-d30379b76b69" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_00e8091a-dfad-4395-b3e6-757f67089f34" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_439093e4-b09f-4701-b31f-e30eff2aa03f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_a97b37fd-5177-4605-b6a9-d30379b76b69" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_439093e4-b09f-4701-b31f-e30eff2aa03f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_96c7e552-86fd-4364-9a7c-21d5b2a31182" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_a97b37fd-5177-4605-b6a9-d30379b76b69" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_96c7e552-86fd-4364-9a7c-21d5b2a31182" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_cc2af1b8-c9c4-41f6-885b-bc85fe8ef75a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9b5099f4-07e9-4c75-93f8-6469fd54a2d3" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9b5099f4-07e9-4c75-93f8-6469fd54a2d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b02ae774-e928-45c8-91e6-0ca6b7197a80" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9b5099f4-07e9-4c75-93f8-6469fd54a2d3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b02ae774-e928-45c8-91e6-0ca6b7197a80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_103d5d22-47ca-4a42-b730-949560a2d1f6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9b5099f4-07e9-4c75-93f8-6469fd54a2d3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_103d5d22-47ca-4a42-b730-949560a2d1f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_0f12d55b-5ab8-4fa9-8836-f99c985f3555" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9b5099f4-07e9-4c75-93f8-6469fd54a2d3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_0f12d55b-5ab8-4fa9-8836-f99c985f3555" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_bee469b4-a880-42ed-a027-aa1af6e07a99" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_9b5099f4-07e9-4c75-93f8-6469fd54a2d3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_bee469b4-a880-42ed-a027-aa1af6e07a99" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_52423917-6d48-4273-a2b7-536dc41d5332" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_21c59911-2276-443a-8f39-eaae8bab8307" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_21c59911-2276-443a-8f39-eaae8bab8307" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_576636a6-acce-4791-8ebf-96a616bd5a67" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_576636a6-acce-4791-8ebf-96a616bd5a67" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_156e751b-6101-4c7a-b940-89d68df7e73c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_156e751b-6101-4c7a-b940-89d68df7e73c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_992a4f6d-a0f8-4424-aee5-cf5e9f0c1159" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod_992a4f6d-a0f8-4424-aee5-cf5e9f0c1159" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_dacf7a75-9b13-485d-8195-6d1e1a397215" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_478e46aa-001a-4d11-b99a-4c0d639cde3b" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_dacf7a75-9b13-485d-8195-6d1e1a397215" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_7d50b719-e9cc-4a00-99b2-7bf9178ca37b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b6b7c03b-fce0-4244-b0c9-3a56e56d614e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_b6b7c03b-fce0-4244-b0c9-3a56e56d614e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_ee48f06d-db12-4e4c-a848-37769e28262c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_ee48f06d-db12-4e4c-a848-37769e28262c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_2f638ac6-0702-4bc1-ac12-0870db667b4d" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_2f638ac6-0702-4bc1-ac12-0870db667b4d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_e6d1dbd9-52f4-4acd-a8ec-f6287c92a4d1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice_e6d1dbd9-52f4-4acd-a8ec-f6287c92a4d1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_fb7400d4-fd57-4600-a2c1-90275ce84fbc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_d9deee3b-a6e3-4591-9ca2-9ad4c251d7ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_fb7400d4-fd57-4600-a2c1-90275ce84fbc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_f3e6ef1c-37f5-4cb5-9a47-da127feca0d8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_b4b6df6d-4e09-4cc7-8346-cd4f6e59d81a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_b4b6df6d-4e09-4cc7-8346-cd4f6e59d81a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_22361917-443d-4c31-8b76-847050c4ad66" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_22361917-443d-4c31-8b76-847050c4ad66" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_1f6ee28f-9677-42c9-b3a1-47aeeb5a352e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_22361917-443d-4c31-8b76-847050c4ad66" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_1f6ee28f-9677-42c9-b3a1-47aeeb5a352e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_ae75be77-50c8-46df-9b7c-5027e0e47792" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_91dbb168-024a-44fe-8efa-7c6fd7d3ee66" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestAbstract_22361917-443d-4c31-8b76-847050c4ad66" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_91dbb168-024a-44fe-8efa-7c6fd7d3ee66" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_6acb0c46-657d-4adb-95cd-458bf64f91dc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_e6707bcd-fa46-4dba-b381-35a05a416d3b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_a77d0f4f-6e6a-478a-923a-1448581d1e72" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_a77d0f4f-6e6a-478a-923a-1448581d1e72" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_a63c203b-a07a-41d5-a7aa-fbe5cfc3e827" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_a77d0f4f-6e6a-478a-923a-1448581d1e72" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_a63c203b-a07a-41d5-a7aa-fbe5cfc3e827" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_be946f1e-ed5e-439f-8408-92539d0046a0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_a77d0f4f-6e6a-478a-923a-1448581d1e72" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_be946f1e-ed5e-439f-8408-92539d0046a0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_462a5506-e140-4d05-b9f8-e1675fe13c58" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_a77d0f4f-6e6a-478a-923a-1448581d1e72" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue_462a5506-e140-4d05-b9f8-e1675fe13c58" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_baf1985b-3cfb-4b30-aeb4-2fc80b0f51c8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValueAbstract_a77d0f4f-6e6a-478a-923a-1448581d1e72" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue_baf1985b-3cfb-4b30-aeb4-2fc80b0f51c8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue_21973186-eae0-4fb0-aa8c-e31114714c7a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_8ff7cd99-27a4-48bb-87f5-350226977b19" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_8ff7cd99-27a4-48bb-87f5-350226977b19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_ff12f355-fcdd-4d57-a855-bfc6bb799796" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_ff12f355-fcdd-4d57-a855-bfc6bb799796" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_efe75919-eb74-4e19-bea7-4d9223ede7da" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_aff3b3f4-b8e7-48c2-ad5f-620f9f6a4189" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_e8c80698-5b94-4867-98c5-6e2c08bfe8fc" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_e8c80698-5b94-4867-98c5-6e2c08bfe8fc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_c9422dc6-8e29-4735-a148-4c8663135901" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_c9422dc6-8e29-4735-a148-4c8663135901" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_f2a25282-2b55-493b-9c01-069dcc7e26b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_f2a25282-2b55-493b-9c01-069dcc7e26b9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_9c6d59fb-1074-4773-af06-7e93d5f7d8a6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_9c6d59fb-1074-4773-af06-7e93d5f7d8a6" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_ff1feff8-a4a2-48bb-a238-5fc09e617746" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_ff1feff8-a4a2-48bb-a238-5fc09e617746" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_b6633bf2-6dd7-41f0-bedf-4a6e51e5b319" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_f5f4a26c-98f5-4882-9fe5-ff2079c45d8c" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_b6633bf2-6dd7-41f0-bedf-4a6e51e5b319" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_60b4efda-2536-43af-b086-cb473f663d0b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_18348ffd-4450-40bc-8886-e30592e293d1" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_60b4efda-2536-43af-b086-cb473f663d0b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_b97f1f20-e6ae-4ea3-a6de-fe290866de5c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_60b4efda-2536-43af-b086-cb473f663d0b" xlink:to="loc_us-gaap_StatementClassOfStockAxis_b97f1f20-e6ae-4ea3-a6de-fe290866de5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b97f1f20-e6ae-4ea3-a6de-fe290866de5c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_b97f1f20-e6ae-4ea3-a6de-fe290866de5c" xlink:to="loc_us-gaap_ClassOfStockDomain_b97f1f20-e6ae-4ea3-a6de-fe290866de5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_7b1a966c-d225-4ac6-a0a6-bba82e9635e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_b97f1f20-e6ae-4ea3-a6de-fe290866de5c" xlink:to="loc_us-gaap_ClassOfStockDomain_7b1a966c-d225-4ac6-a0a6-bba82e9635e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_3ee780cc-0c91-43a3-8b5a-0358b59472df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7b1a966c-d225-4ac6-a0a6-bba82e9635e4" xlink:to="loc_us-gaap_EmployeeStockOptionMember_3ee780cc-0c91-43a3-8b5a-0358b59472df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeAxis_98e3cfb9-03ca-4950-9ead-ad9061323fb9" xlink:href="bah-20210331.xsd#bah_DividendTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_60b4efda-2536-43af-b086-cb473f663d0b" xlink:to="loc_bah_DividendTypeAxis_98e3cfb9-03ca-4950-9ead-ad9061323fb9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeDomain_98e3cfb9-03ca-4950-9ead-ad9061323fb9_default" xlink:href="bah-20210331.xsd#bah_DividendTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_DividendTypeAxis_98e3cfb9-03ca-4950-9ead-ad9061323fb9" xlink:to="loc_bah_DividendTypeDomain_98e3cfb9-03ca-4950-9ead-ad9061323fb9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_DividendTypeDomain_a962978d-43ff-4486-bc65-682a3042070f" xlink:href="bah-20210331.xsd#bah_DividendTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_DividendTypeAxis_98e3cfb9-03ca-4950-9ead-ad9061323fb9" xlink:to="loc_bah_DividendTypeDomain_a962978d-43ff-4486-bc65-682a3042070f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_OrdinaryCashDividendMember_0f4cccb4-caf6-45c0-ab8c-0ff079d3717b" xlink:href="bah-20210331.xsd#bah_OrdinaryCashDividendMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_DividendTypeDomain_a962978d-43ff-4486-bc65-682a3042070f" xlink:to="loc_bah_OrdinaryCashDividendMember_0f4cccb4-caf6-45c0-ab8c-0ff079d3717b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_0197ddf7-281f-4d97-9e1b-2838cd6854e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_60b4efda-2536-43af-b086-cb473f663d0b" xlink:to="loc_us-gaap_PlanNameAxis_0197ddf7-281f-4d97-9e1b-2838cd6854e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_0197ddf7-281f-4d97-9e1b-2838cd6854e8_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_0197ddf7-281f-4d97-9e1b-2838cd6854e8" xlink:to="loc_us-gaap_PlanNameDomain_0197ddf7-281f-4d97-9e1b-2838cd6854e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_ea1fa825-ad1f-44ab-88ea-a9bdf61bc278" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_0197ddf7-281f-4d97-9e1b-2838cd6854e8" xlink:to="loc_us-gaap_PlanNameDomain_ea1fa825-ad1f-44ab-88ea-a9bdf61bc278" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_9f254d15-e37c-43fe-991c-db08ee619fe7" xlink:href="bah-20210331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_ea1fa825-ad1f-44ab-88ea-a9bdf61bc278" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_9f254d15-e37c-43fe-991c-db08ee619fe7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_07bc3965-39d7-4a24-87a4-053deb0b8886" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_60b4efda-2536-43af-b086-cb473f663d0b" xlink:to="loc_us-gaap_AwardTypeAxis_07bc3965-39d7-4a24-87a4-053deb0b8886" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_07bc3965-39d7-4a24-87a4-053deb0b8886_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_07bc3965-39d7-4a24-87a4-053deb0b8886" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_07bc3965-39d7-4a24-87a4-053deb0b8886_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_110d4b79-2b54-4a25-a28d-c38dd22db75e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_07bc3965-39d7-4a24-87a4-053deb0b8886" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_110d4b79-2b54-4a25-a28d-c38dd22db75e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_4430ecd5-a396-4548-9713-e06acd126df0" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_110d4b79-2b54-4a25-a28d-c38dd22db75e" xlink:to="loc_us-gaap_EmployeeStockOptionMember_4430ecd5-a396-4548-9713-e06acd126df0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationEmployeeStockpurchasePlanDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#StockBasedCompensationEmployeeStockpurchasePlanDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationEmployeeStockpurchasePlanDetails" xlink:type="extended" id="i8734b61e295544b2af66f48e99eab451_StockBasedCompensationEmployeeStockpurchasePlanDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bcf9a3c3-16d3-4ae6-bde7-525ac0a6e070" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_7c846897-ce29-4346-a093-c8950ddfb186" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bcf9a3c3-16d3-4ae6-bde7-525ac0a6e070" xlink:to="loc_us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased_7c846897-ce29-4346-a093-c8950ddfb186" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_StockRepurchaseProgramSharesRepurchasedDiscountPercentage_be72b09b-f217-4eed-bae8-6432f81582a8" xlink:href="bah-20210331.xsd#bah_StockRepurchaseProgramSharesRepurchasedDiscountPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bcf9a3c3-16d3-4ae6-bde7-525ac0a6e070" xlink:to="loc_bah_StockRepurchaseProgramSharesRepurchasedDiscountPercentage_be72b09b-f217-4eed-bae8-6432f81582a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_01475b64-7b85-4ede-968f-4740ecf47e1a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bcf9a3c3-16d3-4ae6-bde7-525ac0a6e070" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_01475b64-7b85-4ede-968f-4740ecf47e1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_013342b1-0fd8-4567-b17e-0df73a0b6b7e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bcf9a3c3-16d3-4ae6-bde7-525ac0a6e070" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_013342b1-0fd8-4567-b17e-0df73a0b6b7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_0081d8c3-85b1-4ce8-8eb7-4517075ce991" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_013342b1-0fd8-4567-b17e-0df73a0b6b7e" xlink:to="loc_us-gaap_StatementClassOfStockAxis_0081d8c3-85b1-4ce8-8eb7-4517075ce991" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_0081d8c3-85b1-4ce8-8eb7-4517075ce991_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0081d8c3-85b1-4ce8-8eb7-4517075ce991" xlink:to="loc_us-gaap_ClassOfStockDomain_0081d8c3-85b1-4ce8-8eb7-4517075ce991_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_3df6970d-8661-4633-ad0f-0b97f9f237c6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_0081d8c3-85b1-4ce8-8eb7-4517075ce991" xlink:to="loc_us-gaap_ClassOfStockDomain_3df6970d-8661-4633-ad0f-0b97f9f237c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_cfe4b949-6040-417c-bbb5-632aaa7ed4fa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_3df6970d-8661-4633-ad0f-0b97f9f237c6" xlink:to="loc_us-gaap_CommonClassAMember_cfe4b949-6040-417c-bbb5-632aaa7ed4fa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_a342bd36-b58f-4bbd-a96b-5cf892b451b5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_013342b1-0fd8-4567-b17e-0df73a0b6b7e" xlink:to="loc_us-gaap_PlanNameAxis_a342bd36-b58f-4bbd-a96b-5cf892b451b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_a342bd36-b58f-4bbd-a96b-5cf892b451b5_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_a342bd36-b58f-4bbd-a96b-5cf892b451b5" xlink:to="loc_us-gaap_PlanNameDomain_a342bd36-b58f-4bbd-a96b-5cf892b451b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_bd6e6cd0-68a2-4778-a113-d44ccf85e7c4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_a342bd36-b58f-4bbd-a96b-5cf892b451b5" xlink:to="loc_us-gaap_PlanNameDomain_bd6e6cd0-68a2-4778-a113-d44ccf85e7c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_64812f1e-31dc-4a86-b32b-5a3b05c06569" xlink:href="bah-20210331.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_bd6e6cd0-68a2-4778-a113-d44ccf85e7c4" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_64812f1e-31dc-4a86-b32b-5a3b05c06569" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails" xlink:type="extended" id="i33a5d2ad696640c98ebc712f73091f27_FairValueMeasurementsScheduleofRecurringFairValueMeasurementsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5f6f185c-0c0e-4af3-a807-a627485262fb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_63372a1b-3f3b-4ead-b5e6-53d17eae83f4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5f6f185c-0c0e-4af3-a807-a627485262fb" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_63372a1b-3f3b-4ead-b5e6-53d17eae83f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_34db8f88-1382-4530-9dda-b157be57abf5" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_63372a1b-3f3b-4ead-b5e6-53d17eae83f4" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_34db8f88-1382-4530-9dda-b157be57abf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsFairValueDisclosure_942933be-d2bb-4fe6-8f2c-812081db38eb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_63372a1b-3f3b-4ead-b5e6-53d17eae83f4" xlink:to="loc_us-gaap_OtherAssetsFairValueDisclosure_942933be-d2bb-4fe6-8f2c-812081db38eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5f6f185c-0c0e-4af3-a807-a627485262fb" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_84b12fb0-faa1-4580-aee8-f316f64a1a50" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_84b12fb0-faa1-4580-aee8-f316f64a1a50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_a7f28645-bbcd-4f1d-96f8-5e36c1d6feaa" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_a7f28645-bbcd-4f1d-96f8-5e36c1d6feaa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_bcc44f93-06bc-44b2-b391-cfa920ee8632" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_bcc44f93-06bc-44b2-b391-cfa920ee8632" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_1374963a-9f36-4aaa-b8b5-ccde9a38848a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_1374963a-9f36-4aaa-b8b5-ccde9a38848a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_023cb114-a24b-4816-ba30-838cf1954034" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_ac2c1168-68e4-40ab-b3d2-1f28ed019d4c" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_023cb114-a24b-4816-ba30-838cf1954034" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_70cba68e-12c3-4f2a-a305-a6083131e093" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_5f6f185c-0c0e-4af3-a807-a627485262fb" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_70cba68e-12c3-4f2a-a305-a6083131e093" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_970b037a-817c-4729-ae15-c1a4be374e13" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_70cba68e-12c3-4f2a-a305-a6083131e093" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_970b037a-817c-4729-ae15-c1a4be374e13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_970b037a-817c-4729-ae15-c1a4be374e13_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_970b037a-817c-4729-ae15-c1a4be374e13" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_970b037a-817c-4729-ae15-c1a4be374e13_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_f0179ca2-ffcf-4693-b5b4-85d4b042faae" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_970b037a-817c-4729-ae15-c1a4be374e13" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_f0179ca2-ffcf-4693-b5b4-85d4b042faae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_70439c23-c17d-4a5d-a957-0454777cceb6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_f0179ca2-ffcf-4693-b5b4-85d4b042faae" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_70439c23-c17d-4a5d-a957-0454777cceb6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3b14f8c0-5896-4694-b6c9-f6d692237c10" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_70cba68e-12c3-4f2a-a305-a6083131e093" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3b14f8c0-5896-4694-b6c9-f6d692237c10" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_3b14f8c0-5896-4694-b6c9-f6d692237c10_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3b14f8c0-5896-4694-b6c9-f6d692237c10" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_3b14f8c0-5896-4694-b6c9-f6d692237c10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_5676d539-cef7-4705-aa6a-0a588c321a16" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_3b14f8c0-5896-4694-b6c9-f6d692237c10" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_5676d539-cef7-4705-aa6a-0a588c321a16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_3f816b3f-9cfd-48a3-9c59-6a360eb25b58" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_5676d539-cef7-4705-aa6a-0a588c321a16" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_3f816b3f-9cfd-48a3-9c59-6a360eb25b58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e1227449-17cf-4ad2-9448-5d1113748bb1" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_70cba68e-12c3-4f2a-a305-a6083131e093" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e1227449-17cf-4ad2-9448-5d1113748bb1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1227449-17cf-4ad2-9448-5d1113748bb1_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e1227449-17cf-4ad2-9448-5d1113748bb1" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e1227449-17cf-4ad2-9448-5d1113748bb1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b3a5001e-4abc-4b07-b972-d8823dbee322" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e1227449-17cf-4ad2-9448-5d1113748bb1" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b3a5001e-4abc-4b07-b972-d8823dbee322" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_6e1dfa72-23c8-4a31-adf7-0449c5b234ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b3a5001e-4abc-4b07-b972-d8823dbee322" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_6e1dfa72-23c8-4a31-adf7-0449c5b234ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_b6ac82d8-63ed-4344-90e9-9507367fb143" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b3a5001e-4abc-4b07-b972-d8823dbee322" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_b6ac82d8-63ed-4344-90e9-9507367fb143" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_3c3563ba-eaf8-4af1-9fb3-5cc3f72da44c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_b3a5001e-4abc-4b07-b972-d8823dbee322" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_3c3563ba-eaf8-4af1-9fb3-5cc3f72da44c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RelatedPartyTransactionsDetails" xlink:type="extended" id="i059c53d2aac84a8ea4edfd575fa5dd15_RelatedPartyTransactionsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_201dbb0e-1978-4545-8144-0d10213445b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_NumberofDirectors_c534b693-c8a6-47ba-96d9-518825685863" xlink:href="bah-20210331.xsd#bah_NumberofDirectors"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_201dbb0e-1978-4545-8144-0d10213445b9" xlink:to="loc_bah_NumberofDirectors_c534b693-c8a6-47ba-96d9-518825685863" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_aff3b86b-cbbd-456f-8378-ffd33b9dd182" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_201dbb0e-1978-4545-8144-0d10213445b9" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_aff3b86b-cbbd-456f-8378-ffd33b9dd182" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1eb45f7d-f379-4213-9c74-243189e52329" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_201dbb0e-1978-4545-8144-0d10213445b9" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1eb45f7d-f379-4213-9c74-243189e52329" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_853e1a31-c2f6-4643-8ec9-34c19cede499" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1eb45f7d-f379-4213-9c74-243189e52329" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_853e1a31-c2f6-4643-8ec9-34c19cede499" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_853e1a31-c2f6-4643-8ec9-34c19cede499_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_853e1a31-c2f6-4643-8ec9-34c19cede499" xlink:to="loc_us-gaap_RelatedPartyDomain_853e1a31-c2f6-4643-8ec9-34c19cede499_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_9d782207-91fc-4d75-8fe3-4bfe8197d844" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_853e1a31-c2f6-4643-8ec9-34c19cede499" xlink:to="loc_us-gaap_RelatedPartyDomain_9d782207-91fc-4d75-8fe3-4bfe8197d844" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AffiliatedEntityMember_d61f7291-e53b-4270-90fe-3c8b4aeada06" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_AffiliatedEntityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_9d782207-91fc-4d75-8fe3-4bfe8197d844" xlink:to="loc_srt_AffiliatedEntityMember_d61f7291-e53b-4270-90fe-3c8b4aeada06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_9bb809ce-4a52-4e0c-a1bd-59e67f2b85ba" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_1eb45f7d-f379-4213-9c74-243189e52329" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_9bb809ce-4a52-4e0c-a1bd-59e67f2b85ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_9bb809ce-4a52-4e0c-a1bd-59e67f2b85ba_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_9bb809ce-4a52-4e0c-a1bd-59e67f2b85ba" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_9bb809ce-4a52-4e0c-a1bd-59e67f2b85ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_92443d98-d80a-4c45-8939-b0c41b899d9f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_9bb809ce-4a52-4e0c-a1bd-59e67f2b85ba" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_92443d98-d80a-4c45-8939-b0c41b899d9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_ServicesPerformedUnderSubcontractorMember_0a0a182a-5086-4780-ab44-96b1283c1417" xlink:href="bah-20210331.xsd#bah_ServicesPerformedUnderSubcontractorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_92443d98-d80a-4c45-8939-b0c41b899d9f" xlink:to="loc_bah_ServicesPerformedUnderSubcontractorMember_0a0a182a-5086-4780-ab44-96b1283c1417" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsandContingenciesGovernmentContractingandGuaranteesDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#CommitmentsandContingenciesGovernmentContractingandGuaranteesDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsandContingenciesGovernmentContractingandGuaranteesDetails" xlink:type="extended" id="i19780b9538b54de6b191f35c7d4a1817_CommitmentsandContingenciesGovernmentContractingandGuaranteesDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_9d995d9d-d1c4-4515-b8ee-1a45545bfb73" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_9d995d9d-d1c4-4515-b8ee-1a45545bfb73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsLiquidationProceeds_9981393a-7a1c-4370-bedf-24275be0519c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GuaranteeObligationsLiquidationProceeds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:to="loc_us-gaap_GuaranteeObligationsLiquidationProceeds_9981393a-7a1c-4370-bedf-24275be0519c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_GuarantorObligationsFacility_be51c765-8e50-42c8-bb38-4d3cd72991e0" xlink:href="bah-20210331.xsd#bah_GuarantorObligationsFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:to="loc_bah_GuarantorObligationsFacility_be51c765-8e50-42c8-bb38-4d3cd72991e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_GuarantorObligationsAvailableAmount_3139f8bd-8cc2-445d-b803-15a94b684fb9" xlink:href="bah-20210331.xsd#bah_GuarantorObligationsAvailableAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:to="loc_bah_GuarantorObligationsAvailableAmount_3139f8bd-8cc2-445d-b803-15a94b684fb9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_f4b345da-06c8-4b16-b12d-0cd3714d87ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_f4b345da-06c8-4b16-b12d-0cd3714d87ed" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_2c043f01-1098-47c8-bb5d-78e20c9b4ab2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_faaa50d6-9be5-45bc-b571-0d9053fa1866" xlink:to="loc_us-gaap_ConcentrationRiskTable_2c043f01-1098-47c8-bb5d-78e20c9b4ab2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_b3e150f6-7e3b-4fad-a9ae-a39f1bbb6e60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_2c043f01-1098-47c8-bb5d-78e20c9b4ab2" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_b3e150f6-7e3b-4fad-a9ae-a39f1bbb6e60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_b3e150f6-7e3b-4fad-a9ae-a39f1bbb6e60_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_b3e150f6-7e3b-4fad-a9ae-a39f1bbb6e60" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_b3e150f6-7e3b-4fad-a9ae-a39f1bbb6e60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_667829c9-2d07-4ee9-b82b-35ad01b22241" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_b3e150f6-7e3b-4fad-a9ae-a39f1bbb6e60" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_667829c9-2d07-4ee9-b82b-35ad01b22241" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialStandbyLetterOfCreditMember_6fcb515b-4f85-4048-ad96-e05a20b453e8" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinancialStandbyLetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_667829c9-2d07-4ee9-b82b-35ad01b22241" xlink:to="loc_us-gaap_FinancialStandbyLetterOfCreditMember_6fcb515b-4f85-4048-ad96-e05a20b453e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_bbe78831-63d4-4622-917c-6526fca32a79" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_2c043f01-1098-47c8-bb5d-78e20c9b4ab2" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_bbe78831-63d4-4622-917c-6526fca32a79" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_bbe78831-63d4-4622-917c-6526fca32a79_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_bbe78831-63d4-4622-917c-6526fca32a79" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_bbe78831-63d4-4622-917c-6526fca32a79_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_b05407da-4684-4110-9e97-75b268c5ba88" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_bbe78831-63d4-4622-917c-6526fca32a79" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_b05407da-4684-4110-9e97-75b268c5ba88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_3d93dbf1-03bd-402b-b58e-c485872d142c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_b05407da-4684-4110-9e97-75b268c5ba88" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_3d93dbf1-03bd-402b-b58e-c485872d142c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_400fda7d-32f1-4d59-87ed-c87dfb70f0c7" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_d5b6308b-0e6a-4583-9ea6-7fd30c570548" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_400fda7d-32f1-4d59-87ed-c87dfb70f0c7" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_d5b6308b-0e6a-4583-9ea6-7fd30c570548" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_9adb6bbb-b3f9-492e-964a-6513bad971bb" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_400fda7d-32f1-4d59-87ed-c87dfb70f0c7" xlink:to="loc_us-gaap_LossContingenciesTable_9adb6bbb-b3f9-492e-964a-6513bad971bb" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_980b2d35-691f-40fd-a2f7-e90e94eb31be" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_9adb6bbb-b3f9-492e-964a-6513bad971bb" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_980b2d35-691f-40fd-a2f7-e90e94eb31be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_980b2d35-691f-40fd-a2f7-e90e94eb31be_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_980b2d35-691f-40fd-a2f7-e90e94eb31be" xlink:to="loc_us-gaap_LossContingencyNatureDomain_980b2d35-691f-40fd-a2f7-e90e94eb31be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_2ed529bf-6929-4863-acf8-04e3543d4b68" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_980b2d35-691f-40fd-a2f7-e90e94eb31be" xlink:to="loc_us-gaap_LossContingencyNatureDomain_2ed529bf-6929-4863-acf8-04e3543d4b68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnfavorableRegulatoryActionMember_448bdfe6-4425-4e40-92e8-449946b586df" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnfavorableRegulatoryActionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_2ed529bf-6929-4863-acf8-04e3543d4b68" xlink:to="loc_us-gaap_UnfavorableRegulatoryActionMember_448bdfe6-4425-4e40-92e8-449946b586df" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/SupplementalFinancialInformationDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#SupplementalFinancialInformationDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SupplementalFinancialInformationDetails" xlink:type="extended" id="i83e50962a5924c209b6eefa1c2c4998e_SupplementalFinancialInformationDetails">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_f0c31ece-8cbf-4f6b-b159-fce234db33ae" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_ff9a681f-35e6-4066-8bf6-73a78e739607" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_f0c31ece-8cbf-4f6b-b159-fce234db33ae" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_ff9a681f-35e6-4066-8bf6-73a78e739607" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_69095801-7790-46eb-8b6a-6e94e5750edf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_ff9a681f-35e6-4066-8bf6-73a78e739607" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_69095801-7790-46eb-8b6a-6e94e5750edf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_e62b62ee-9a73-4fe8-8988-bbd311f53c2c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_ff9a681f-35e6-4066-8bf6-73a78e739607" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_e62b62ee-9a73-4fe8-8988-bbd311f53c2c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_e619aeef-15e7-4aa0-a038-d0e807120e61" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDeductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_ff9a681f-35e6-4066-8bf6-73a78e739607" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_e619aeef-15e7-4aa0-a038-d0e807120e61" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_b4144f26-374e-48b4-81a2-ec09f2802f6e" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_432da4be-d051-4d3d-a2d5-1d47bd916208" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_f0c31ece-8cbf-4f6b-b159-fce234db33ae" xlink:to="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_432da4be-d051-4d3d-a2d5-1d47bd916208" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_c72ceeed-0ed8-4d5c-b3a0-51a9b155444c" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_432da4be-d051-4d3d-a2d5-1d47bd916208" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_c72ceeed-0ed8-4d5c-b3a0-51a9b155444c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_c72ceeed-0ed8-4d5c-b3a0-51a9b155444c_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_c72ceeed-0ed8-4d5c-b3a0-51a9b155444c" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_c72ceeed-0ed8-4d5c-b3a0-51a9b155444c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_d71ac6c7-a551-4f7f-9d67-06618b9001ac" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_c72ceeed-0ed8-4d5c-b3a0-51a9b155444c" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_d71ac6c7-a551-4f7f-9d67-06618b9001ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_SECSchedule1209ValuationAllowanceAccountsReceivableMember_dc59d0d5-a732-40ce-9a2f-01ef510648c4" xlink:href="bah-20210331.xsd#bah_SECSchedule1209ValuationAllowanceAccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_d71ac6c7-a551-4f7f-9d67-06618b9001ac" xlink:to="loc_bah_SECSchedule1209ValuationAllowanceAccountsReceivableMember_dc59d0d5-a732-40ce-9a2f-01ef510648c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_d46a94c4-37b3-4b19-98c7-69786e8893e4" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_d71ac6c7-a551-4f7f-9d67-06618b9001ac" xlink:to="loc_us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember_d46a94c4-37b3-4b19-98c7-69786e8893e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1b145009-088c-4b24-8e40-7ae1a5a7d3bd" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_432da4be-d051-4d3d-a2d5-1d47bd916208" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1b145009-088c-4b24-8e40-7ae1a5a7d3bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1b145009-088c-4b24-8e40-7ae1a5a7d3bd_default" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1b145009-088c-4b24-8e40-7ae1a5a7d3bd" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_1b145009-088c-4b24-8e40-7ae1a5a7d3bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_7e96a0d8-7674-47d0-8068-8ad79b9053c2" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionAxis_1b145009-088c-4b24-8e40-7ae1a5a7d3bd" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_7e96a0d8-7674-47d0-8068-8ad79b9053c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_0a9b8673-0eba-4489-852d-2d52a6878238" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_CumulativeEffectPeriodOfAdoptionDomain_7e96a0d8-7674-47d0-8068-8ad79b9053c2" xlink:to="loc_srt_CumulativeEffectPeriodOfAdoptionAdjustmentMember_0a9b8673-0eba-4489-852d-2d52a6878238" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.boozallen.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="bah-20210331.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/SubsequentEventsDetails" xlink:type="extended" id="i6c20d387b75144bd8991cf0933579c51_SubsequentEventsDetails">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_a2603413-1387-4ede-9dd9-0c7fc82d6993" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_a2603413-1387-4ede-9dd9-0c7fc82d6993" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_ad9b2bf9-cda0-49ed-81c4-987df7891d60" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_ad9b2bf9-cda0-49ed-81c4-987df7891d60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_2f68f5aa-a7c6-46b1-b525-3a93c4cfaa95" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_2f68f5aa-a7c6-46b1-b525-3a93c4cfaa95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_4aca881b-1eea-4d69-aa12-883dc677f795" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_4aca881b-1eea-4d69-aa12-883dc677f795" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_935df469-2cc7-4b26-8f45-4b8eb6d934b9" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_935df469-2cc7-4b26-8f45-4b8eb6d934b9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_ab10882e-52a8-4aa7-8197-90e270914770" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_5dcd7129-619d-465f-8345-78e0f76f9da6" xlink:to="loc_us-gaap_SubsequentEventTable_ab10882e-52a8-4aa7-8197-90e270914770" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_a83b3d85-a200-48d8-85f7-54996f24442b" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ab10882e-52a8-4aa7-8197-90e270914770" xlink:to="loc_us-gaap_AwardTypeAxis_a83b3d85-a200-48d8-85f7-54996f24442b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a83b3d85-a200-48d8-85f7-54996f24442b_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_a83b3d85-a200-48d8-85f7-54996f24442b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a83b3d85-a200-48d8-85f7-54996f24442b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e36605ec-8ad9-405e-9256-451fa577f2c2" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_a83b3d85-a200-48d8-85f7-54996f24442b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e36605ec-8ad9-405e-9256-451fa577f2c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_55c4ab79-2f21-483f-809e-f2ccbc3645ee" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e36605ec-8ad9-405e-9256-451fa577f2c2" xlink:to="loc_us-gaap_RestrictedStockMember_55c4ab79-2f21-483f-809e-f2ccbc3645ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_03abbfd4-5fd8-4d2a-898e-2b57dc557536" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ab10882e-52a8-4aa7-8197-90e270914770" xlink:to="loc_us-gaap_StatementClassOfStockAxis_03abbfd4-5fd8-4d2a-898e-2b57dc557536" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_03abbfd4-5fd8-4d2a-898e-2b57dc557536_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_03abbfd4-5fd8-4d2a-898e-2b57dc557536" xlink:to="loc_us-gaap_ClassOfStockDomain_03abbfd4-5fd8-4d2a-898e-2b57dc557536_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c82d7cb5-0ba2-4d83-83fc-f6b5689ad0ed" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_03abbfd4-5fd8-4d2a-898e-2b57dc557536" xlink:to="loc_us-gaap_ClassOfStockDomain_c82d7cb5-0ba2-4d83-83fc-f6b5689ad0ed" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_78851d49-1227-44be-a6fc-cfdc40330d36" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_c82d7cb5-0ba2-4d83-83fc-f6b5689ad0ed" xlink:to="loc_us-gaap_CommonClassAMember_78851d49-1227-44be-a6fc-cfdc40330d36" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_098afdc7-262e-4454-84c8-a3424c1c4eaf" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ab10882e-52a8-4aa7-8197-90e270914770" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_098afdc7-262e-4454-84c8-a3424c1c4eaf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_098afdc7-262e-4454-84c8-a3424c1c4eaf_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_098afdc7-262e-4454-84c8-a3424c1c4eaf" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_098afdc7-262e-4454-84c8-a3424c1c4eaf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_7e409b42-f5ea-4506-84a5-1be5a53f2d1a" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_098afdc7-262e-4454-84c8-a3424c1c4eaf" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_7e409b42-f5ea-4506-84a5-1be5a53f2d1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_025ac76c-8e99-4f98-a242-8b82ebc34890" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_7e409b42-f5ea-4506-84a5-1be5a53f2d1a" xlink:to="loc_us-gaap_SubsequentEventMember_025ac76c-8e99-4f98-a242-8b82ebc34890" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_e15e61f6-90c1-4e2f-93d5-f6df078b260f" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_ab10882e-52a8-4aa7-8197-90e270914770" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_e15e61f6-90c1-4e2f-93d5-f6df078b260f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e15e61f6-90c1-4e2f-93d5-f6df078b260f_default" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e15e61f6-90c1-4e2f-93d5-f6df078b260f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_e15e61f6-90c1-4e2f-93d5-f6df078b260f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b7ae8262-da56-42d3-bd8f-cda45b731790" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_e15e61f6-90c1-4e2f-93d5-f6df078b260f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b7ae8262-da56-42d3-bd8f-cda45b731790" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bah_LibertyITSolutionsLLCMember_0020e9e6-6745-4474-a395-5a90d6ec1392" xlink:href="bah-20210331.xsd#bah_LibertyITSolutionsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_b7ae8262-da56-42d3-bd8f-cda45b731790" xlink:to="loc_bah_LibertyITSolutionsLLCMember_0020e9e6-6745-4474-a395-5a90d6ec1392" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
