<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpenses" xlink:href="bah-20200630.xsd#AccountsPayableAndOtherAccruedExpenses" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesDetails" xlink:href="bah-20200630.xsd#AccountsPayableAndOtherAccruedExpensesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesTables" xlink:href="bah-20200630.xsd#AccountsPayableAndOtherAccruedExpensesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsReceivableNetOfAllowance" xlink:href="bah-20200630.xsd#AccountsReceivableNetOfAllowance" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceDetails" xlink:href="bah-20200630.xsd#AccountsReceivableNetOfAllowanceDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceTables" xlink:href="bah-20200630.xsd#AccountsReceivableNetOfAllowanceTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccruedCompensationAndBenefits" xlink:href="bah-20200630.xsd#AccruedCompensationAndBenefits" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccruedCompensationAndBenefitsDetails" xlink:href="bah-20200630.xsd#AccruedCompensationAndBenefitsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccruedCompensationAndBenefitsTables" xlink:href="bah-20200630.xsd#AccruedCompensationAndBenefitsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLoss" xlink:href="bah-20200630.xsd#AccumulatedOtherComprehensiveLoss" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossReclassificationsOutOfAccumulatedOtherComprehensiveLossToNetIncomeDetails" xlink:href="bah-20200630.xsd#AccumulatedOtherComprehensiveLossReclassificationsOutOfAccumulatedOtherComprehensiveLossToNetIncomeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleOfChangesInAociDetails" xlink:href="bah-20200630.xsd#AccumulatedOtherComprehensiveLossScheduleOfChangesInAociDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossTables" xlink:href="bah-20200630.xsd#AccumulatedOtherComprehensiveLossTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BasisOfPresentation" xlink:href="bah-20200630.xsd#BasisOfPresentation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BasisOfPresentationPolicies" xlink:href="bah-20200630.xsd#BasisOfPresentationPolicies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BusinessOverview" xlink:href="bah-20200630.xsd#BusinessOverview" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/BusinessOverviewDetails" xlink:href="bah-20200630.xsd#BusinessOverviewDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingencies" xlink:href="bah-20200630.xsd#CommitmentsAndContingencies" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingenciesGuaranteesAndContractsDetails" xlink:href="bah-20200630.xsd#CommitmentsAndContingenciesGuaranteesAndContractsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CommitmentsAndContingenciesLitigationDetails" xlink:href="bah-20200630.xsd#CommitmentsAndContingenciesLitigationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedBalanceSheets" xlink:href="bah-20200630.xsd#CondensedConsolidatedBalanceSheets" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:href="bah-20200630.xsd#CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:href="bah-20200630.xsd#CondensedConsolidatedStatementsOfCashFlows" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:href="bah-20200630.xsd#CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfOperations" xlink:href="bah-20200630.xsd#CondensedConsolidatedStatementsOfOperations" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfStockholdersEquityUnaudited" xlink:href="bah-20200630.xsd#CondensedConsolidatedStatementsOfStockholdersEquityUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical" xlink:href="bah-20200630.xsd#CondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Cover" xlink:href="bah-20200630.xsd#Cover" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Debt" xlink:href="bah-20200630.xsd#Debt" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:href="bah-20200630.xsd#DebtNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleOfDebtDetails" xlink:href="bah-20200630.xsd#DebtScheduleOfDebtDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtScheduleOfInterestExpenseDetails" xlink:href="bah-20200630.xsd#DebtScheduleOfInterestExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DebtTables" xlink:href="bah-20200630.xsd#DebtTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Derivatives" xlink:href="bah-20200630.xsd#Derivatives" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesNarrativeDetails" xlink:href="bah-20200630.xsd#DerivativesNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesScheduleOfEffectOfDerivativesOnFinancialStatementsDetails" xlink:href="bah-20200630.xsd#DerivativesScheduleOfEffectOfDerivativesOnFinancialStatementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/DerivativesTables" xlink:href="bah-20200630.xsd#DerivativesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShare" xlink:href="bah-20200630.xsd#EarningsPerShare" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:href="bah-20200630.xsd#EarningsPerShareDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EarningsPerShareTables" xlink:href="bah-20200630.xsd#EarningsPerShareTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlans" xlink:href="bah-20200630.xsd#EmployeeBenefitPlans" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansDetails" xlink:href="bah-20200630.xsd#EmployeeBenefitPlansDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/EmployeeBenefitPlansTables" xlink:href="bah-20200630.xsd#EmployeeBenefitPlansTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurements" xlink:href="bah-20200630.xsd#FairValueMeasurements" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsDetails" xlink:href="bah-20200630.xsd#FairValueMeasurementsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/FairValueMeasurementsTables" xlink:href="bah-20200630.xsd#FairValueMeasurementsTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxes" xlink:href="bah-20200630.xsd#IncomeTaxes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/IncomeTaxesDetails" xlink:href="bah-20200630.xsd#IncomeTaxesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Leases" xlink:href="bah-20200630.xsd#Leases" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/LeasesMinimumFutureObligationsForOperatingLeasesDetails" xlink:href="bah-20200630.xsd#LeasesMinimumFutureObligationsForOperatingLeasesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/LeasesScheduleOfLeaseCostDetails" xlink:href="bah-20200630.xsd#LeasesScheduleOfLeaseCostDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/LeasesSupplementalCashFlowAndOtherInformationDetails" xlink:href="bah-20200630.xsd#LeasesSupplementalCashFlowAndOtherInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/LeasesTables" xlink:href="bah-20200630.xsd#LeasesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilities" xlink:href="bah-20200630.xsd#OtherLongTermLiabilities" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilitiesDetails" xlink:href="bah-20200630.xsd#OtherLongTermLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/OtherLongTermLiabilitiesTables" xlink:href="bah-20200630.xsd#OtherLongTermLiabilitiesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RelatedPartyTransactions" xlink:href="bah-20200630.xsd#RelatedPartyTransactions" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RelatedPartyTransactionsDetails" xlink:href="bah-20200630.xsd#RelatedPartyTransactionsDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/Revenue" xlink:href="bah-20200630.xsd#Revenue" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:href="bah-20200630.xsd#RevenueNarrativeDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueScheduleOfContractAssetsAndLiabilitiesDetails" xlink:href="bah-20200630.xsd#RevenueScheduleOfContractAssetsAndLiabilitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueSchedulesOfDisaggregationOfRevenueDetails" xlink:href="bah-20200630.xsd#RevenueSchedulesOfDisaggregationOfRevenueDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/RevenueTables" xlink:href="bah-20200630.xsd#RevenueTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensation" xlink:href="bah-20200630.xsd#StockBasedCompensation" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationScheduleOfStockBasedCompensationExpenseDetails" xlink:href="bah-20200630.xsd#StockBasedCompensationScheduleOfStockBasedCompensationExpenseDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationStockPlansDetails" xlink:href="bah-20200630.xsd#StockBasedCompensationStockPlansDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationTables" xlink:href="bah-20200630.xsd#StockBasedCompensationTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.boozallen.com/role/StockBasedCompensationUnrecognizedCompensationDetails" xlink:href="bah-20200630.xsd#StockBasedCompensationUnrecognizedCompensationDetails" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpenses" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_A62D053D13D65D8E8EA5F16FAC63FA52" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_E7152A06E941540687A6AC2B8DB4692D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_A62D053D13D65D8E8EA5F16FAC63FA52" xlink:to="loc_us-gaap_LossContingenciesTable_E7152A06E941540687A6AC2B8DB4692D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_2581AB9F9BF8521F980A4298818CA577" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_E7152A06E941540687A6AC2B8DB4692D" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_2581AB9F9BF8521F980A4298818CA577" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_8D001EA84F3E3CA5F34AF82A70BCE21C_99D0C3207C1D579E98D46CDE2E6181E3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_2581AB9F9BF8521F980A4298818CA577" xlink:to="loc_us-gaap_LossContingencyNatureDomain_8D001EA84F3E3CA5F34AF82A70BCE21C_99D0C3207C1D579E98D46CDE2E6181E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_4C012DD4A36D5D0F8A3FCD4B337412A1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_2581AB9F9BF8521F980A4298818CA577" xlink:to="loc_us-gaap_LossContingencyNatureDomain_4C012DD4A36D5D0F8A3FCD4B337412A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnfavorableRegulatoryActionMember" xlink:label="loc_us-gaap_UnfavorableRegulatoryActionMember_199FE19B2E6C5DBC9CDD3376B42720D7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_4C012DD4A36D5D0F8A3FCD4B337412A1" xlink:to="loc_us-gaap_UnfavorableRegulatoryActionMember_199FE19B2E6C5DBC9CDD3376B42720D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_79257419F60C5BC586C29E16F4DF517B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_A62D053D13D65D8E8EA5F16FAC63FA52" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_79257419F60C5BC586C29E16F4DF517B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsPayableAndOtherAccruedExpensesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsReceivableNetOfAllowance" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccountsReceivableNetOfAllowanceTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccruedCompensationAndBenefits" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccruedCompensationAndBenefitsDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccruedCompensationAndBenefitsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLoss" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossReclassificationsOutOfAccumulatedOtherComprehensiveLossToNetIncomeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems" xlink:label="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_68795FB7609C6B75309B9FD068189986" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_58CB9F470E406299C9A59FD06814D961" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_68795FB7609C6B75309B9FD068189986" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_58CB9F470E406299C9A59FD06814D961" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_03CBF0D7B33BA879061D9FD068153722" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_58CB9F470E406299C9A59FD06814D961" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_03CBF0D7B33BA879061D9FD068153722" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ADB91D92C6E8943573C89FD06816FE70_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_03CBF0D7B33BA879061D9FD068153722" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ADB91D92C6E8943573C89FD06816FE70_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ADB91D92C6E8943573C89FD06816FE70" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis_03CBF0D7B33BA879061D9FD068153722" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ADB91D92C6E8943573C89FD06816FE70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_F89EF09B58545E2D947F9FD0681604F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeDomain_ADB91D92C6E8943573C89FD06816FE70" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember_F89EF09B58545E2D947F9FD0681604F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_6FF8F77D0D0B979DB7D29FD06817219A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_58CB9F470E406299C9A59FD06814D961" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_6FF8F77D0D0B979DB7D29FD06817219A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_95F442465634842DC3019FD06817F034_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6FF8F77D0D0B979DB7D29FD06817219A" xlink:to="loc_us-gaap_EquityComponentDomain_95F442465634842DC3019FD06817F034_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_95F442465634842DC3019FD06817F034" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_6FF8F77D0D0B979DB7D29FD06817219A" xlink:to="loc_us-gaap_EquityComponentDomain_95F442465634842DC3019FD06817F034" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_F6E7C91C7DB02DE0E0439FD068175159" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_95F442465634842DC3019FD06817F034" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_F6E7C91C7DB02DE0E0439FD068175159" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_803D352FFE98B780ED819FD06818E634" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_95F442465634842DC3019FD06817F034" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_803D352FFE98B780ED819FD06818E634" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_0DFB7E49364BAFEA93949FD06818E973" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_68795FB7609C6B75309B9FD068189986" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_0DFB7E49364BAFEA93949FD06818E973" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_B9593BD236E0D75B6ACF9FD06818A36A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_68795FB7609C6B75309B9FD068189986" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_B9593BD236E0D75B6ACF9FD06818A36A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_54341779ED893A9DFCCC9FD0681A4D76" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReclassificationAdjustmentOutOfAccumulatedOtherComprehensiveIncomeLineItems_68795FB7609C6B75309B9FD068189986" xlink:to="loc_us-gaap_NetIncomeLoss_54341779ED893A9DFCCC9FD0681A4D76" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossScheduleOfChangesInAociDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_3F7DE7CEF8D12784E7503A2E831E0DC9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_CF73B5E2DE127C34DC0A3A2E831CAC60" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_3F7DE7CEF8D12784E7503A2E831E0DC9" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_CF73B5E2DE127C34DC0A3A2E831CAC60" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_80794362A7B0FFB71E183A2E831C5B8A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_CF73B5E2DE127C34DC0A3A2E831CAC60" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_80794362A7B0FFB71E183A2E831C5B8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_80794362A7B0FFB71E183A2E831C5B8A" xlink:to="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_80794362A7B0FFB71E183A2E831C5B8A" xlink:to="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_A47FDC0CB828A1766CDC3A2E831DD5B4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_A47FDC0CB828A1766CDC3A2E831DD5B4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_9C225E28295DF0EF4F593A2E831D66F8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_9C225E28295DF0EF4F593A2E831D66F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F5F7531E689D49102E123A2E831E466A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_BC727E23DAC28A0B886E3A2E831DFFD4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F5F7531E689D49102E123A2E831E466A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_3F7DE7CEF8D12784E7503A2E831E0DC9" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_1E80F739288BB35C06C23A2E831FFB21" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:to="loc_us-gaap_StockholdersEquity_1E80F739288BB35C06C23A2E831FFB21" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_C574CD8D0CCFA5242DD83A2E831F34F9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_C574CD8D0CCFA5242DD83A2E831F34F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_26B9D0E867AD97D972C53A2E8320A877" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_26B9D0E867AD97D972C53A2E8320A877" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_807FC6F13A2A5051DFBB3A2E83202E4C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_807FC6F13A2A5051DFBB3A2E83202E4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_4540A5D6DDD79B4CBE0F3A2E8320A9E3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_96ECFA99B6461E880B1F3A2E831EE481" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_4540A5D6DDD79B4CBE0F3A2E8320A9E3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/AccumulatedOtherComprehensiveLossTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BasisOfPresentation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BasisOfPresentationPolicies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BusinessOverview" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/BusinessOverviewDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingencies" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingenciesGuaranteesAndContractsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskLineItems" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTable" xlink:label="loc_us-gaap_ConcentrationRiskTable_53784BB47D617F1D910454A492A52855" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:to="loc_us-gaap_ConcentrationRiskTable_53784BB47D617F1D910454A492A52855" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GuaranteeObligationsByNatureAxis" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_ACDDBFD7F521C56E9CCA54A492A5A420" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_53784BB47D617F1D910454A492A52855" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_ACDDBFD7F521C56E9CCA54A492A5A420" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_1DBE2A20611D4C95460554A492A51EA2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_ACDDBFD7F521C56E9CCA54A492A5A420" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_1DBE2A20611D4C95460554A492A51EA2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GuaranteeObligationsNatureDomain" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_1DBE2A20611D4C95460554A492A51EA2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_ACDDBFD7F521C56E9CCA54A492A5A420" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_1DBE2A20611D4C95460554A492A51EA2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialStandbyLetterOfCreditMember" xlink:label="loc_us-gaap_FinancialStandbyLetterOfCreditMember_C099E28E02D898D8BD7454A492A65690" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_1DBE2A20611D4C95460554A492A51EA2" xlink:to="loc_us-gaap_FinancialStandbyLetterOfCreditMember_C099E28E02D898D8BD7454A492A65690" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_B8462AF5217C45DB0C6854A492A6BB63" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_53784BB47D617F1D910454A492A52855" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_B8462AF5217C45DB0C6854A492A6BB63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_8AC037ADF5B9FBF60C7F54A492A6C995_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_B8462AF5217C45DB0C6854A492A6BB63" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_8AC037ADF5B9FBF60C7F54A492A6C995_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_8AC037ADF5B9FBF60C7F54A492A6C995" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_B8462AF5217C45DB0C6854A492A6BB63" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_8AC037ADF5B9FBF60C7F54A492A6C995" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GovernmentContractsConcentrationRiskMember" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_9B113363873019F42D0154A492A6C1DB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_8AC037ADF5B9FBF60C7F54A492A6C995" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_9B113363873019F42D0154A492A6C1DB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_7BF323E183258F4730C254A492A73FBE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_7BF323E183258F4730C254A492A73FBE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GuaranteeObligationsLiquidationProceeds" xlink:label="loc_us-gaap_GuaranteeObligationsLiquidationProceeds_4484F0A8948A7D4B533554A492AD0516" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:to="loc_us-gaap_GuaranteeObligationsLiquidationProceeds_4484F0A8948A7D4B533554A492AD0516" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_GuarantorObligationsFacility" xlink:label="loc_bah_GuarantorObligationsFacility_710616A1947125D5887354A492AD45BF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:to="loc_bah_GuarantorObligationsFacility_710616A1947125D5887354A492AD45BF" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_GuarantorObligationsAvailableAmount" xlink:label="loc_bah_GuarantorObligationsAvailableAmount_CF95F175DFFA158022D654A492AD4BB8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:to="loc_bah_GuarantorObligationsAvailableAmount_CF95F175DFFA158022D654A492AD4BB8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_23732A22D9D28548A7E254A492AD78B5" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_A2BA470A6C9713B5885754A492A60672" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_23732A22D9D28548A7E254A492AD78B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_5EEB2C070CF46D96D20954A492AE5DFE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_F396347EAC823B5D309154A492AD720C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_5EEB2C070CF46D96D20954A492AE5DFE" xlink:to="loc_us-gaap_LossContingenciesTable_F396347EAC823B5D309154A492AD720C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_CE49BEA6D0F2BF741D2C54A492AD490D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_F396347EAC823B5D309154A492AD720C" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_CE49BEA6D0F2BF741D2C54A492AD490D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_A5918C54916EA3B25B5454A492AD0EE1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_CE49BEA6D0F2BF741D2C54A492AD490D" xlink:to="loc_us-gaap_LossContingencyNatureDomain_A5918C54916EA3B25B5454A492AD0EE1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_A5918C54916EA3B25B5454A492AD0EE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_CE49BEA6D0F2BF741D2C54A492AD490D" xlink:to="loc_us-gaap_LossContingencyNatureDomain_A5918C54916EA3B25B5454A492AD0EE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnfavorableRegulatoryActionMember" xlink:label="loc_us-gaap_UnfavorableRegulatoryActionMember_9607D851B8D76DDF99DB54A492AEE080" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_A5918C54916EA3B25B5454A492AD0EE1" xlink:to="loc_us-gaap_UnfavorableRegulatoryActionMember_9607D851B8D76DDF99DB54A492AEE080" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_B986F77AAC1B345A6EB254A492AE4CA7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_5EEB2C070CF46D96D20954A492AE5DFE" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_B986F77AAC1B345A6EB254A492AE4CA7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CommitmentsAndContingenciesLitigationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_C7D34A94868D1363062154A48FC06F59" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_A7F33650019F607B2FC154A48FBE91F1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_C7D34A94868D1363062154A48FC06F59" xlink:to="loc_us-gaap_LossContingenciesTable_A7F33650019F607B2FC154A48FBE91F1" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseAxis" xlink:label="loc_srt_LitigationCaseAxis_ADB61DDC396829B4AA7D54A48FBE0BD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A7F33650019F607B2FC154A48FBE91F1" xlink:to="loc_srt_LitigationCaseAxis_ADB61DDC396829B4AA7D54A48FBE0BD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_94ED3337D9BA3AFF66BD54A48FBF7C33_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_ADB61DDC396829B4AA7D54A48FBE0BD7" xlink:to="loc_srt_LitigationCaseTypeDomain_94ED3337D9BA3AFF66BD54A48FBF7C33_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_94ED3337D9BA3AFF66BD54A48FBF7C33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_ADB61DDC396829B4AA7D54A48FBE0BD7" xlink:to="loc_srt_LitigationCaseTypeDomain_94ED3337D9BA3AFF66BD54A48FBF7C33" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_UnitedStatesDistrictCourtForTheEasternDistrictOfVirginiaStyledLangleyV.BoozAllenHamiltonHoldingCorp.Member" xlink:label="loc_bah_UnitedStatesDistrictCourtForTheEasternDistrictOfVirginiaStyledLangleyV.BoozAllenHamiltonHoldingCorp.Member_C7DEB479F7FB2302DFAB54A48FBF8E81" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_94ED3337D9BA3AFF66BD54A48FBF7C33" xlink:to="loc_bah_UnitedStatesDistrictCourtForTheEasternDistrictOfVirginiaStyledLangleyV.BoozAllenHamiltonHoldingCorp.Member_C7DEB479F7FB2302DFAB54A48FBF8E81" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNumberOfPlaintiffs" xlink:label="loc_us-gaap_LossContingencyNumberOfPlaintiffs_9DEFC14E54697995CB6E54A48FC09940" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_C7D34A94868D1363062154A48FC06F59" xlink:to="loc_us-gaap_LossContingencyNumberOfPlaintiffs_9DEFC14E54697995CB6E54A48FC09940" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedBalanceSheets" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedBalanceSheetsParenthetical" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfCashFlows" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfComprehensiveIncome" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfOperations" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfStockholdersEquityUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_ACE0D2C5759CF1A601388BF1249FFA3E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_439C428F08B0BDD5C28A8BF12497BC08" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_ACE0D2C5759CF1A601388BF1249FFA3E" xlink:to="loc_us-gaap_StatementTable_439C428F08B0BDD5C28A8BF12497BC08" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="bah-20200630.xsd#bah_CumulativeEffectPeriodOfAdoptionAxis" xlink:label="loc_bah_CumulativeEffectPeriodOfAdoptionAxis_ECB9D197B3A0BDE7AC5C8BF12497CE32" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_439C428F08B0BDD5C28A8BF12497BC08" xlink:to="loc_bah_CumulativeEffectPeriodOfAdoptionAxis_ECB9D197B3A0BDE7AC5C8BF12497CE32" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="loc_bah_CumulativeEffectPeriodOfAdoptionDomain_502233DA42112F6103C28BF12497C80B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_bah_CumulativeEffectPeriodOfAdoptionAxis_ECB9D197B3A0BDE7AC5C8BF12497CE32" xlink:to="loc_bah_CumulativeEffectPeriodOfAdoptionDomain_502233DA42112F6103C28BF12497C80B_default" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_CumulativeEffectPeriodOfAdoptionDomain" xlink:label="loc_bah_CumulativeEffectPeriodOfAdoptionDomain_502233DA42112F6103C28BF12497C80B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_bah_CumulativeEffectPeriodOfAdoptionAxis_ECB9D197B3A0BDE7AC5C8BF12497CE32" xlink:to="loc_bah_CumulativeEffectPeriodOfAdoptionDomain_502233DA42112F6103C28BF12497C80B" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_CumulativeEffectPeriodOfAdoptionAdjustmentMember" xlink:label="loc_bah_CumulativeEffectPeriodOfAdoptionAdjustmentMember_6FBEC3CDC38E70C2EFFF8BF12497EAD1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bah_CumulativeEffectPeriodOfAdoptionDomain_502233DA42112F6103C28BF12497C80B" xlink:to="loc_bah_CumulativeEffectPeriodOfAdoptionAdjustmentMember_6FBEC3CDC38E70C2EFFF8BF12497EAD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_5FFD80D5F17D5137F89F8BF124970B26" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_439C428F08B0BDD5C28A8BF12497BC08" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_5FFD80D5F17D5137F89F8BF124970B26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5FFD80D5F17D5137F89F8BF124970B26" xlink:to="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5FFD80D5F17D5137F89F8BF124970B26" xlink:to="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_F1FF19F3735FC430E6E98BF124975134" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63" xlink:to="loc_us-gaap_TreasuryStockMember_F1FF19F3735FC430E6E98BF124975134" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_F76A1918950B41824DB88BF12497F266" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_F76A1918950B41824DB88BF12497F266" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_EF59CAED641F819D22EA8BF12497A3FF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63" xlink:to="loc_us-gaap_RetainedEarningsMember_EF59CAED641F819D22EA8BF12497A3FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_D994A4CACCDD4160FE268BF12497B67D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_E050F83097D3069FE7F38BF124978A63" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_D994A4CACCDD4160FE268BF12497B67D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_31EF906DA02E37659D038BF124977D92" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_439C428F08B0BDD5C28A8BF12497BC08" xlink:to="loc_us-gaap_StatementClassOfStockAxis_31EF906DA02E37659D038BF124977D92" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_8DBB951A7025D819A3218BF124972F63_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_31EF906DA02E37659D038BF124977D92" xlink:to="loc_us-gaap_ClassOfStockDomain_8DBB951A7025D819A3218BF124972F63_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_8DBB951A7025D819A3218BF124972F63" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_31EF906DA02E37659D038BF124977D92" xlink:to="loc_us-gaap_ClassOfStockDomain_8DBB951A7025D819A3218BF124972F63" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_4FEF343EC87CF8DE35F78BF124975C2C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_8DBB951A7025D819A3218BF124972F63" xlink:to="loc_us-gaap_CommonClassAMember_4FEF343EC87CF8DE35F78BF124975C2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_ACE0D2C5759CF1A601388BF1249FFA3E" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_E0D3CE07154BFC966F5F8BF1249F6155" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_SharesOutstanding_E0D3CE07154BFC966F5F8BF1249F6155" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_7A325EE690DAEDD4EE928BF1249FD9BC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_StockholdersEquity_7A325EE690DAEDD4EE928BF1249FD9BC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_4A83B9F4A2D52B9CB2F78BF1249FC57A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_4A83B9F4A2D52B9CB2F78BF1249FC57A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_555F7EB8805FA99ACC9D8BF1249FE3E2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_555F7EB8805FA99ACC9D8BF1249FE3E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_BAF46E5473F151657BC48BF1249F09A1" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_BAF46E5473F151657BC48BF1249F09A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_BC986CABAEC89E1BE8048BF1249F8A03" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_BC986CABAEC89E1BE8048BF1249F8A03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_77499289A299D80DAEFF8BF1249F0FEF" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_77499289A299D80DAEFF8BF1249F0FEF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_0B333AC81327A3D60AF68BF1249F30A1" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_0B333AC81327A3D60AF68BF1249F30A1" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureRestrictedStockUnitsVesting" xlink:label="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureRestrictedStockUnitsVesting_0C53430BA359DECD88D98BF1249F6167" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureRestrictedStockUnitsVesting_0C53430BA359DECD88D98BF1249F6167" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureStockOptionExercises" xlink:label="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureStockOptionExercises_FB6C5A87C924A80082F48BF1249F3912" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_bah_AdjustmentsToAdditionalPaidInCapitalRecognitionOfLiabilityRelatedToFutureStockOptionExercises_FB6C5A87C924A80082F48BF1249F3912" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_6E857259217FD1070B8C8BF1249FDCBB" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_NetIncomeLoss_6E857259217FD1070B8C8BF1249FDCBB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_5D7A4EC4BF07F7A023AA8BF1249F26D1" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_5D7A4EC4BF07F7A023AA8BF1249F26D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DividendsCash" xlink:label="loc_us-gaap_DividendsCash_71F023D4BB223E7ED08C8BF1249FF658" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_DividendsCash_71F023D4BB223E7ED08C8BF1249FF658" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_C5F19AE2EB079AF3AAAF8BF1249FCFBA" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_1897CDC1ACBC3D992C838BF1249FA345" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_C5F19AE2EB079AF3AAAF8BF1249FCFBA" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/CondensedConsolidatedStatementsOfStockholdersEquityUnauditedParenthetical" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_D6F783E1C4C3553BB72A39E5044058A2" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_8AA013270E16C8A392ED39E5043E04BA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_D6F783E1C4C3553BB72A39E5044058A2" xlink:to="loc_us-gaap_StatementTable_8AA013270E16C8A392ED39E5043E04BA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_B0F0EA84D709EA57814439E5043F0534" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_8AA013270E16C8A392ED39E5043E04BA" xlink:to="loc_us-gaap_StatementClassOfStockAxis_B0F0EA84D709EA57814439E5043F0534" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_259ED06A51CCD20C7B0839E5043F6ED2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B0F0EA84D709EA57814439E5043F0534" xlink:to="loc_us-gaap_ClassOfStockDomain_259ED06A51CCD20C7B0839E5043F6ED2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_259ED06A51CCD20C7B0839E5043F6ED2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_B0F0EA84D709EA57814439E5043F0534" xlink:to="loc_us-gaap_ClassOfStockDomain_259ED06A51CCD20C7B0839E5043F6ED2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_663DE7B8D40D03315E2D39E5043F39C9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_259ED06A51CCD20C7B0839E5043F6ED2" xlink:to="loc_us-gaap_CommonClassAMember_663DE7B8D40D03315E2D39E5043F39C9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockDividendsPerShareCashPaid" xlink:label="loc_us-gaap_CommonStockDividendsPerShareCashPaid_271C6C730C965BD8C90039E50440EB80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D6F783E1C4C3553BB72A39E5044058A2" xlink:to="loc_us-gaap_CommonStockDividendsPerShareCashPaid_271C6C730C965BD8C90039E50440EB80" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_F60BF24BBFB06E83F67439E504404BE4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D6F783E1C4C3553BB72A39E5044058A2" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_F60BF24BBFB06E83F67439E504404BE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_822C6C5F6DB4038D1F2C39E504402264" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_D6F783E1C4C3553BB72A39E5044058A2" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_822C6C5F6DB4038D1F2C39E504402264" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Cover" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Debt" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_D56EED0D7F5C699D8E6B78928BCC6FF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_D56EED0D7F5C699D8E6B78928BCC6FF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_D56EED0D7F5C699D8E6B78928BCC6FF4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_D56EED0D7F5C699D8E6B78928BCC6FF4" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_DA894AE8D0E0EDF2817D78928BCD47C1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_DA894AE8D0E0EDF2817D78928BCD47C1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_2229F21216F07CCB93A578928BCEADE3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_2229F21216F07CCB93A578928BCEADE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPeriodThreeMember" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_78FEAE66A5C3887F0B6A78928BCE49BD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_53E9E945457336DD927878928BCD7482" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodThreeMember_78FEAE66A5C3887F0B6A78928BCE49BD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_CE3A1F9ADABEAF1CF2A878928BCE02AB" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_HedgingDesignationAxis_CE3A1F9ADABEAF1CF2A878928BCE02AB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_DC76F96BFF2B3C8565A978928BCEC26F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_CE3A1F9ADABEAF1CF2A878928BCE02AB" xlink:to="loc_us-gaap_HedgingDesignationDomain_DC76F96BFF2B3C8565A978928BCEC26F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_DC76F96BFF2B3C8565A978928BCEC26F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_CE3A1F9ADABEAF1CF2A878928BCE02AB" xlink:to="loc_us-gaap_HedgingDesignationDomain_DC76F96BFF2B3C8565A978928BCEC26F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_D244413886E9D655458978928BCFDA42" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_DC76F96BFF2B3C8565A978928BCEC26F" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_D244413886E9D655458978928BCFDA42" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_AD7EB1BCBFAA9F5C105278928BCFDE02" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_AD7EB1BCBFAA9F5C105278928BCFDE02" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1E18E925BCA4D036603F78928BCF3F96_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_AD7EB1BCBFAA9F5C105278928BCFDE02" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1E18E925BCA4D036603F78928BCF3F96_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1E18E925BCA4D036603F78928BCF3F96" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_AD7EB1BCBFAA9F5C105278928BCFDE02" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1E18E925BCA4D036603F78928BCF3F96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_98F6328BC7875FE2DAFD78928BD06A8C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1E18E925BCA4D036603F78928BCF3F96" xlink:to="loc_us-gaap_InterestRateSwapMember_98F6328BC7875FE2DAFD78928BD06A8C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FA11C81E4CCE4CE9477478928BD0ADFF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FA11C81E4CCE4CE9477478928BD0ADFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_2663350D559F873B34E978928BD0D798_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FA11C81E4CCE4CE9477478928BD0ADFF" xlink:to="loc_us-gaap_HedgingRelationshipDomain_2663350D559F873B34E978928BD0D798_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_2663350D559F873B34E978928BD0D798" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_FA11C81E4CCE4CE9477478928BD0ADFF" xlink:to="loc_us-gaap_HedgingRelationshipDomain_2663350D559F873B34E978928BD0D798" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_0ED52BBADCED6BFA0F8978928BD0F6D1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_2663350D559F873B34E978928BD0D798" xlink:to="loc_us-gaap_CashFlowHedgingMember_0ED52BBADCED6BFA0F8978928BD0F6D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_252CF6EC16105A60709678928BD0D371" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_252CF6EC16105A60709678928BD0D371" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_252CF6EC16105A60709678928BD0D371" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_252CF6EC16105A60709678928BD0D371" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_75150648E1E6C8FC8B1178928BD1B169" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1" xlink:to="loc_us-gaap_SecuredDebtMember_75150648E1E6C8FC8B1178928BD1B169" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_A4D5B450781B4C7B6CB178928BD22BEE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_A4D5B450781B4C7B6CB178928BD22BEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_6701F6F83FA35035D5AF78928BD2563D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1" xlink:to="loc_us-gaap_LetterOfCreditMember_6701F6F83FA35035D5AF78928BD2563D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_B284D5E376DB8E36E6AB78928BD256E9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_603011FBB2E7EBD7854678928BD14DF1" xlink:to="loc_us-gaap_SeniorNotesMember_B284D5E376DB8E36E6AB78928BD256E9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_989A7FB8EE38623D730378928BD29C6D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_DebtInstrumentAxis_989A7FB8EE38623D730378928BD29C6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_989A7FB8EE38623D730378928BD29C6D" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_989A7FB8EE38623D730378928BD29C6D" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_6C8F9A357C711D664A8F78928BD38DD5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6" xlink:to="loc_bah_TrancheBLoansMember_6C8F9A357C711D664A8F78928BD38DD5" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_BC37A82D6243C07C272578928BD3F79D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6" xlink:to="loc_bah_TrancheALoansMember_BC37A82D6243C07C272578928BD3F79D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_3B105D078AFADE58B89178928BD39CA4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_3B105D078AFADE58B89178928BD39CA4" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_SeniorNotesDue2025Member" xlink:label="loc_bah_SeniorNotesDue2025Member_062B2BD999FD258538C278928BD3F92A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_06D39B9697C021C1461478928BD2CAE6" xlink:to="loc_bah_SeniorNotesDue2025Member_062B2BD999FD258538C278928BD3F92A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_23A4312A853F87B8E28478928BD3F5D9" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_us-gaap_VariableRateAxis_23A4312A853F87B8E28478928BD3F5D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_23A4312A853F87B8E28478928BD3F5D9" xlink:to="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_23A4312A853F87B8E28478928BD3F5D9" xlink:to="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_6906224C000E268E044478928BD47045" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_6906224C000E268E044478928BD47045" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaap_BaseRateMember_EC03996E2143C2EB8E6178928BD485B3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B" xlink:to="loc_us-gaap_BaseRateMember_EC03996E2143C2EB8E6178928BD485B3" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_OvernightFederalFundsRateMember" xlink:label="loc_bah_OvernightFederalFundsRateMember_F3A290A139B916ED43EC78928BD4CB72" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_FFD702CA79FB51EA051A78928BD43F3B" xlink:to="loc_bah_OvernightFederalFundsRateMember_F3A290A139B916ED43EC78928BD4CB72" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_16E930B70952BBD0936A78928BD576BA" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_6EA37CBF4DFE470A6A8178928BCC84D3" xlink:to="loc_srt_RangeAxis_16E930B70952BBD0936A78928BD576BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_BEA909066AA192EA8BBB78928BD5C53F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_16E930B70952BBD0936A78928BD576BA" xlink:to="loc_srt_RangeMember_BEA909066AA192EA8BBB78928BD5C53F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_BEA909066AA192EA8BBB78928BD5C53F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_16E930B70952BBD0936A78928BD576BA" xlink:to="loc_srt_RangeMember_BEA909066AA192EA8BBB78928BD5C53F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_BF2814AFA8C7E349CD1778928BD73EAA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_BEA909066AA192EA8BBB78928BD5C53F" xlink:to="loc_srt_MinimumMember_BF2814AFA8C7E349CD1778928BD73EAA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_46CA65BEF5623849163E78928BD9E790" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_BEA909066AA192EA8BBB78928BD5C53F" xlink:to="loc_srt_MaximumMember_46CA65BEF5623849163E78928BD9E790" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_B0FFF71F6AA52F64279F78928BDA209D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_B0FFF71F6AA52F64279F78928BDA209D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_AC6BC083A8A750C3569978928BDAE645" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_AC6BC083A8A750C3569978928BDAE645" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DebtInstrumentDebtCovenantPremiumPayablePercent" xlink:label="loc_bah_DebtInstrumentDebtCovenantPremiumPayablePercent_41270EE6011D6D00603B78928BDA65D8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_bah_DebtInstrumentDebtCovenantPremiumPayablePercent_41270EE6011D6D00603B78928BDA65D8" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DebtInstrumentDebtCovenantPremiumPayableForRepricingTransactionsTerm" xlink:label="loc_bah_DebtInstrumentDebtCovenantPremiumPayableForRepricingTransactionsTerm_6C208BF428CC09BC3B7778928BDBB75F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_bah_DebtInstrumentDebtCovenantPremiumPayableForRepricingTransactionsTerm_6C208BF428CC09BC3B7778928BDBB75F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_FDF9E72B74056D65496078928BDBCA44" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_FDF9E72B74056D65496078928BDBCA44" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_LongtermDebtMaximumExpandedLoanFacility" xlink:label="loc_bah_LongtermDebtMaximumExpandedLoanFacility_175C114A7C72D90F6D9E78928BDB3FD7" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_bah_LongtermDebtMaximumExpandedLoanFacility_175C114A7C72D90F6D9E78928BDB3FD7" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired" xlink:label="loc_bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired_4C0CCD5D361F9031725278928BDB232C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_bah_DebtCovenantExpandedLoanPercentageofConsolidatedEBITDARequired_4C0CCD5D361F9031725278928BDB232C" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DebtInstrumentNetSecuredLeverageRatioMaximum" xlink:label="loc_bah_DebtInstrumentNetSecuredLeverageRatioMaximum_68CC7CBE4D4BAB63F0B678928BDB12B2" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_bah_DebtInstrumentNetSecuredLeverageRatioMaximum_68CC7CBE4D4BAB63F0B678928BDB12B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_FF6B49E05BA1C2441C2778928BDC48C0" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_FF6B49E05BA1C2441C2778928BDC48C0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_BFA66342642C741D8BA378928BDC2B51" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_BFA66342642C741D8BA378928BDC2B51" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_D30D2497551462C33BA378928BDCBF59" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_LineOfCredit_D30D2497551462C33BA378928BDCBF59" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal" xlink:label="loc_bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal_3D59447CFDE7E6A5DBDB78928BDCDD75" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_bah_DebtInstrumentQuarterlyPeriodicPaymentPercentagePrincipal_3D59447CFDE7E6A5DBDB78928BDCDD75" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_EEFB6771C28C6BFFC1E778928BDCEFAD" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_InterestPaid_EEFB6771C28C6BFFC1E778928BDCEFAD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_ECFADC39C6E56BE0B24378928BDD31B2" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_ECFADC39C6E56BE0B24378928BDD31B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_5E7CCCC2F7A74A8CF31C78928BDD71E3" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_5E7CCCC2F7A74A8CF31C78928BDD71E3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_11EF8F7443B4A64910FD78928BDDC19D" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_11EF8F7443B4A64910FD78928BDDC19D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredFinanceCostsGross" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_60E9CCECEE60E6A6963578928BDD88AC" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_60E9CCECEE60E6A6963578928BDD88AC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeNotionalAmount" xlink:label="loc_us-gaap_DerivativeNotionalAmount_904759A64457A96EBDA178928BDE5D40" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_F16635D51C7DEF6C7C5678928BD97CEB" xlink:to="loc_us-gaap_DerivativeNotionalAmount_904759A64457A96EBDA178928BDE5D40" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleOfDebtDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_CEEDBB21977479D5297E3A2E847C771C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_CA8210720D6641D95C603A2E8476C93C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_CEEDBB21977479D5297E3A2E847C771C" xlink:to="loc_us-gaap_DebtInstrumentTable_CA8210720D6641D95C603A2E8476C93C" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_B4617EB6809D2CB7A4B03A2E84774BE2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_CA8210720D6641D95C603A2E8476C93C" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_B4617EB6809D2CB7A4B03A2E84774BE2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1D94CAFF92E4499F73873A2E8478B432_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_B4617EB6809D2CB7A4B03A2E84774BE2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1D94CAFF92E4499F73873A2E8478B432_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1D94CAFF92E4499F73873A2E8478B432" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_B4617EB6809D2CB7A4B03A2E84774BE2" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1D94CAFF92E4499F73873A2E8478B432" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_D41302ACC684DEE8F6513A2E8479B5A3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_1D94CAFF92E4499F73873A2E8478B432" xlink:to="loc_us-gaap_SecuredDebtMember_D41302ACC684DEE8F6513A2E8479B5A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_1C7918FE5B3835A0FEE63A2E8479EB1D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_1D94CAFF92E4499F73873A2E8478B432" xlink:to="loc_us-gaap_SeniorNotesMember_1C7918FE5B3835A0FEE63A2E8479EB1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_535D1AA2E04528B404E53A2E847A581F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_CA8210720D6641D95C603A2E8476C93C" xlink:to="loc_us-gaap_DebtInstrumentAxis_535D1AA2E04528B404E53A2E847A581F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_535D1AA2E04528B404E53A2E847A581F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_535D1AA2E04528B404E53A2E847A581F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_9C9FBB5CFA871BCB39223A2E847A69E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB" xlink:to="loc_bah_TrancheALoansMember_9C9FBB5CFA871BCB39223A2E847A69E6" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_DC13140E00757412AC763A2E847B232F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB" xlink:to="loc_bah_TrancheBLoansMember_DC13140E00757412AC763A2E847B232F" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_RevolverMember" xlink:label="loc_bah_RevolverMember_A33329D3EC66CCCBAF563A7341FBF337" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB" xlink:to="loc_bah_RevolverMember_A33329D3EC66CCCBAF563A7341FBF337" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_SeniorNotesDue2025Member" xlink:label="loc_bah_SeniorNotesDue2025Member_C4199439F709F6FB096C3A2E847BFA6D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5B303DA0F02561A076233A2E847A2FDB" xlink:to="loc_bah_SeniorNotesDue2025Member_C4199439F709F6FB096C3A2E847BFA6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtCurrentAndNoncurrentAbstract" xlink:label="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_CEEDBB21977479D5297E3A2E847C771C" xlink:to="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_E4BC825477344A67E14A3A2E847C4DAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_E4BC825477344A67E14A3A2E847C4DAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCarryingAmount" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_E8B35E9A7EF55622C9D73A2E847D0BE4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_E8B35E9A7EF55622C9D73A2E847D0BE4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_6A200B751B9B774E17633A2E847DE5FC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_6A200B751B9B774E17633A2E847DE5FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebt" xlink:label="loc_us-gaap_LongTermDebt_8480A451E84443504E3B3A2E847D9BC8" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:to="loc_us-gaap_LongTermDebt_8480A451E84443504E3B3A2E847D9BC8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebtCurrent" xlink:label="loc_us-gaap_LongTermDebtCurrent_1997436B61FCD70111003A2E847E537C" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:to="loc_us-gaap_LongTermDebtCurrent_1997436B61FCD70111003A2E847E537C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_F7482CEC301B1BC049973A2E847E0490" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtCurrentAndNoncurrentAbstract_6463B18B4997BF82475C3A2E847CC2B5" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_F7482CEC301B1BC049973A2E847E0490" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtScheduleOfInterestExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_C7E31FEE3502975BA9E354837C077C54" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_us-gaap_DebtInstrumentTable_C7E31FEE3502975BA9E354837C077C54" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_74F6CABFD0B819655E1354837C0740F9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_C7E31FEE3502975BA9E354837C077C54" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_74F6CABFD0B819655E1354837C0740F9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_74F6CABFD0B819655E1354837C0740F9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_74F6CABFD0B819655E1354837C0740F9" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_121C094DAE48BB325CAC54837C08EC48" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338" xlink:to="loc_us-gaap_SecuredDebtMember_121C094DAE48BB325CAC54837C08EC48" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_0C036B6591411C1996C454837C0941F7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_0C036B6591411C1996C454837C0941F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SeniorNotesMember" xlink:label="loc_us-gaap_SeniorNotesMember_A3DA92E211EA0D38378854837C099681" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_0B46C744075DC5BBDF5654837C087338" xlink:to="loc_us-gaap_SeniorNotesMember_A3DA92E211EA0D38378854837C099681" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_C04AA4B6E10A1E795B4354837C0A681F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_C7E31FEE3502975BA9E354837C077C54" xlink:to="loc_us-gaap_DebtInstrumentAxis_C04AA4B6E10A1E795B4354837C0A681F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4F615B1FB97E311114A954837C0B8C2B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_C04AA4B6E10A1E795B4354837C0A681F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4F615B1FB97E311114A954837C0B8C2B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4F615B1FB97E311114A954837C0B8C2B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_C04AA4B6E10A1E795B4354837C0A681F" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4F615B1FB97E311114A954837C0B8C2B" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TrancheALoansMember" xlink:label="loc_bah_TrancheALoansMember_4BF456A3E41DA99C72DD54837C0BB7D0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4F615B1FB97E311114A954837C0B8C2B" xlink:to="loc_bah_TrancheALoansMember_4BF456A3E41DA99C72DD54837C0BB7D0" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TrancheBLoansMember" xlink:label="loc_bah_TrancheBLoansMember_D23BB95A3A136093D94F54837C0C5D1F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4F615B1FB97E311114A954837C0B8C2B" xlink:to="loc_bah_TrancheBLoansMember_D23BB95A3A136093D94F54837C0C5D1F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpenseDebt" xlink:label="loc_us-gaap_InterestExpenseDebt_AB313D3269C5A6A7599C54837C0DEAE4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_us-gaap_InterestExpenseDebt_AB313D3269C5A6A7599C54837C0DEAE4" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DeferredPaymentObligationInterestPayment" xlink:label="loc_bah_DeferredPaymentObligationInterestPayment_33DB13F6EAF459FABF8054837C0DF026" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_bah_DeferredPaymentObligationInterestPayment_33DB13F6EAF459FABF8054837C0DF026" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_38E4CF4B13B246BDF92E54837C0D0785" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_38E4CF4B13B246BDF92E54837C0D0785" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_InterestExpenseDebtInterestSwap" xlink:label="loc_bah_InterestExpenseDebtInterestSwap_AA54BE5D869C4A9FEC0B5496D06F7701" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_bah_InterestExpenseDebtInterestSwap_AA54BE5D869C4A9FEC0B5496D06F7701" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_InterestIncomeExpenseOther" xlink:label="loc_bah_InterestIncomeExpenseOther_4D8AF12E9CA17548845454837C0EB908" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_bah_InterestIncomeExpenseOther_4D8AF12E9CA17548845454837C0EB908" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_4286AACB717D1C85FEE554837C0E8D61" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_E458E368926DF166A10954837C0C46B4" xlink:to="loc_us-gaap_InterestExpense_4286AACB717D1C85FEE554837C0E8D61" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DebtTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Derivatives" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLineItems" xlink:label="loc_us-gaap_DerivativeLineItems_C13678BA6FA1F23D49147DA07C21342C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeTable" xlink:label="loc_us-gaap_DerivativeTable_B70A11701799A95DA6347DA07C1BE04B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_C13678BA6FA1F23D49147DA07C21342C" xlink:to="loc_us-gaap_DerivativeTable_B70A11701799A95DA6347DA07C1BE04B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_18DD191472B2557514A47DA07C1B6B77" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_B70A11701799A95DA6347DA07C1BE04B" xlink:to="loc_us-gaap_HedgingDesignationAxis_18DD191472B2557514A47DA07C1B6B77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_5839CD1B08BAB3F5D2C47DA07C1C348A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_18DD191472B2557514A47DA07C1B6B77" xlink:to="loc_us-gaap_HedgingDesignationDomain_5839CD1B08BAB3F5D2C47DA07C1C348A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_5839CD1B08BAB3F5D2C47DA07C1C348A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_18DD191472B2557514A47DA07C1B6B77" xlink:to="loc_us-gaap_HedgingDesignationDomain_5839CD1B08BAB3F5D2C47DA07C1C348A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_9EC08DE80C23660EF85C7DA07C1C4CEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_5839CD1B08BAB3F5D2C47DA07C1C348A" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_9EC08DE80C23660EF85C7DA07C1C4CEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_84EAF0C7DDD0E9AFDF797DA07C1C475A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_B70A11701799A95DA6347DA07C1BE04B" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_84EAF0C7DDD0E9AFDF797DA07C1C475A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_B1D053A30A9773CEB2C37DA07C1D1B0A_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_84EAF0C7DDD0E9AFDF797DA07C1C475A" xlink:to="loc_us-gaap_HedgingRelationshipDomain_B1D053A30A9773CEB2C37DA07C1D1B0A_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_B1D053A30A9773CEB2C37DA07C1D1B0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_84EAF0C7DDD0E9AFDF797DA07C1C475A" xlink:to="loc_us-gaap_HedgingRelationshipDomain_B1D053A30A9773CEB2C37DA07C1D1B0A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_35604D776B8B532B08067DA07C1D471F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_B1D053A30A9773CEB2C37DA07C1D1B0A" xlink:to="loc_us-gaap_CashFlowHedgingMember_35604D776B8B532B08067DA07C1D471F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_30F81777682960111EF97DA07C1E554F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_B70A11701799A95DA6347DA07C1BE04B" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_30F81777682960111EF97DA07C1E554F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_59A8F15F657AE9BF1A4F7DA07C1ECBEE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_30F81777682960111EF97DA07C1E554F" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_59A8F15F657AE9BF1A4F7DA07C1ECBEE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_59A8F15F657AE9BF1A4F7DA07C1ECBEE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_30F81777682960111EF97DA07C1E554F" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_59A8F15F657AE9BF1A4F7DA07C1ECBEE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherCurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_E1BAB65513CC339C61DD7DA07C1E33A0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_59A8F15F657AE9BF1A4F7DA07C1ECBEE" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_E1BAB65513CC339C61DD7DA07C1E33A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_65792419180C0CE99CA37DA07C1F42DE" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_59A8F15F657AE9BF1A4F7DA07C1ECBEE" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_65792419180C0CE99CA37DA07C1F42DE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_9C4DF3A2E0406632C9557DA07C1FAA0D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_B70A11701799A95DA6347DA07C1BE04B" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_9C4DF3A2E0406632C9557DA07C1FAA0D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_28F7D418E17739107F5C7DA07C20DD9D_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9C4DF3A2E0406632C9557DA07C1FAA0D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_28F7D418E17739107F5C7DA07C20DD9D_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_28F7D418E17739107F5C7DA07C20DD9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_9C4DF3A2E0406632C9557DA07C1FAA0D" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_28F7D418E17739107F5C7DA07C20DD9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_37867E82549EBB1C61657DA07C21064C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_28F7D418E17739107F5C7DA07C20DD9D" xlink:to="loc_us-gaap_InterestRateSwapMember_37867E82549EBB1C61657DA07C21064C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeNotionalAmount" xlink:label="loc_us-gaap_DerivativeNotionalAmount_03A9A839AD7A3AB8E8637DA07C216407" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_C13678BA6FA1F23D49147DA07C21342C" xlink:to="loc_us-gaap_DerivativeNotionalAmount_03A9A839AD7A3AB8E8637DA07C216407" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue" xlink:label="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_9320D294E49AAE8F57D67DA07C21A335" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_C13678BA6FA1F23D49147DA07C21342C" xlink:to="loc_us-gaap_DerivativeInstrumentsInHedgesLiabilitiesAtFairValue_9320D294E49AAE8F57D67DA07C21A335" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_64ABA3BE154BD2B7B40B7DA07C227A88" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_C13678BA6FA1F23D49147DA07C21342C" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet_64ABA3BE154BD2B7B40B7DA07C227A88" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesScheduleOfEffectOfDerivativesOnFinancialStatementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_BFA652F1F94D83F00EFB39CEE528C814" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_A847E940B2AFAF7D493739CEE523792F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_BFA652F1F94D83F00EFB39CEE528C814" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_A847E940B2AFAF7D493739CEE523792F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_B5129CB7469244E0F0F439CEE5249FD3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_A847E940B2AFAF7D493739CEE523792F" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_B5129CB7469244E0F0F439CEE5249FD3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5E44494DB7E6A9AFE40739CEE5241DDF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B5129CB7469244E0F0F439CEE5249FD3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5E44494DB7E6A9AFE40739CEE5241DDF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_5E44494DB7E6A9AFE40739CEE5241DDF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_B5129CB7469244E0F0F439CEE5249FD3" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_5E44494DB7E6A9AFE40739CEE5241DDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_A634EAAE0E021CF6AB6539CEE5252E6E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_5E44494DB7E6A9AFE40739CEE5241DDF" xlink:to="loc_us-gaap_InterestRateSwapMember_A634EAAE0E021CF6AB6539CEE5252E6E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationAxis" xlink:label="loc_us-gaap_HedgingDesignationAxis_541E1C7429BA2E7570A139CEE525F052" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_A847E940B2AFAF7D493739CEE523792F" xlink:to="loc_us-gaap_HedgingDesignationAxis_541E1C7429BA2E7570A139CEE525F052" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_D240709AC0AFB1F7219C39CEE5267AE1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_541E1C7429BA2E7570A139CEE525F052" xlink:to="loc_us-gaap_HedgingDesignationDomain_D240709AC0AFB1F7219C39CEE5267AE1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingDesignationDomain" xlink:label="loc_us-gaap_HedgingDesignationDomain_D240709AC0AFB1F7219C39CEE5267AE1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_541E1C7429BA2E7570A139CEE525F052" xlink:to="loc_us-gaap_HedgingDesignationDomain_D240709AC0AFB1F7219C39CEE5267AE1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DesignatedAsHedgingInstrumentMember" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_458A005ECADF595CEAD039CEE5267301" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_D240709AC0AFB1F7219C39CEE5267AE1" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_458A005ECADF595CEAD039CEE5267301" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_9D93ED7A65CABB76175639CEE527BBC6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_A847E940B2AFAF7D493739CEE523792F" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_9D93ED7A65CABB76175639CEE527BBC6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_A63F8395BCBE9787441539CEE527A625_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_9D93ED7A65CABB76175639CEE527BBC6" xlink:to="loc_us-gaap_HedgingRelationshipDomain_A63F8395BCBE9787441539CEE527A625_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_A63F8395BCBE9787441539CEE527A625" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_9D93ED7A65CABB76175639CEE527BBC6" xlink:to="loc_us-gaap_HedgingRelationshipDomain_A63F8395BCBE9787441539CEE527A625" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_A47AFE8C967B43B1E9B539CEE528A496" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_A63F8395BCBE9787441539CEE527A625" xlink:to="loc_us-gaap_CashFlowHedgingMember_A47AFE8C967B43B1E9B539CEE528A496" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_CB58A6891AF47889E82C39CEE52AD6EE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_BFA652F1F94D83F00EFB39CEE528C814" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax_CB58A6891AF47889E82C39CEE52AD6EE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet" xlink:label="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_4C4D16848CC6A0E9BBB539CEE52A4A6C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_BFA652F1F94D83F00EFB39CEE528C814" xlink:to="loc_us-gaap_InterestRateCashFlowHedgeGainLossReclassifiedToEarningsNet_4C4D16848CC6A0E9BBB539CEE52A4A6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_D62DE008346369C866CA39CEE52A6BE7" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_BFA652F1F94D83F00EFB39CEE528C814" xlink:to="loc_us-gaap_InterestExpense_D62DE008346369C866CA39CEE52A6BE7" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/DerivativesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShare" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareBasicLineItems" xlink:label="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_28F26D5E9DE6C4845D92788412785760" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_28F26D5E9DE6C4845D92788412785760" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_406CDF09697C61B6B1F978841278DCC4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_28F26D5E9DE6C4845D92788412785760" xlink:to="loc_us-gaap_StatementClassOfStockAxis_406CDF09697C61B6B1F978841278DCC4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_36530779B71D86EDE1E5788412795BC1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_406CDF09697C61B6B1F978841278DCC4" xlink:to="loc_us-gaap_ClassOfStockDomain_36530779B71D86EDE1E5788412795BC1_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_36530779B71D86EDE1E5788412795BC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_406CDF09697C61B6B1F978841278DCC4" xlink:to="loc_us-gaap_ClassOfStockDomain_36530779B71D86EDE1E5788412795BC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_EE09E15D3C72363B16727884127949ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_36530779B71D86EDE1E5788412795BC1" xlink:to="loc_us-gaap_CommonClassAMember_EE09E15D3C72363B16727884127949ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_26432A13E3D20443F8F9788412795782" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_28F26D5E9DE6C4845D92788412785760" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_26432A13E3D20443F8F9788412795782" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_8877AA2F9094A2D644FC788412797677_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_26432A13E3D20443F8F9788412795782" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_8877AA2F9094A2D644FC788412797677_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_8877AA2F9094A2D644FC788412797677" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_26432A13E3D20443F8F9788412795782" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_8877AA2F9094A2D644FC788412797677" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_8F9CE7E4D7440F933F347884127AC606" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_8877AA2F9094A2D644FC788412797677" xlink:to="loc_us-gaap_RestrictedStockMember_8F9CE7E4D7440F933F347884127AC606" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_8E50D0B77EA1D4120D9B7884127AA845" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_8877AA2F9094A2D644FC788412797677" xlink:to="loc_us-gaap_EmployeeStockOptionMember_8E50D0B77EA1D4120D9B7884127AA845" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UndistributedEarnings" xlink:label="loc_us-gaap_UndistributedEarnings_B202C928735A440E42B07884127D1FF1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_UndistributedEarnings_B202C928735A440E42B07884127D1FF1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_3CF5476470A1993F53F57884127E880A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_3CF5476470A1993F53F57884127E880A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UndistributedEarningsDiluted" xlink:label="loc_us-gaap_UndistributedEarningsDiluted_71DDD449020AABE1C8C37884127E861C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_UndistributedEarningsDiluted_71DDD449020AABE1C8C37884127E861C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_BA9186117CA4BA3CC01778841280EC09" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_BA9186117CA4BA3CC01778841280EC09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_788622006F61066AD9D97884128063A3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_788622006F61066AD9D97884128063A3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareReconciliationAbstract" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_6FF70AB8225EB2F6969478841280EBB7" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_6FF70AB8225EB2F6969478841280EBB7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_A6425332BABFE198D384788412806F68" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_6FF70AB8225EB2F6969478841280EBB7" xlink:to="loc_us-gaap_EarningsPerShareBasic_A6425332BABFE198D384788412806F68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_FC69E569460331970858788412818DA4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_6FF70AB8225EB2F6969478841280EBB7" xlink:to="loc_us-gaap_EarningsPerShareDiluted_FC69E569460331970858788412818DA4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_3465E4E105F285E23AB8788412827E4F" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToParticipatingNonvestedSharesWithNonForfeitableDividendRights_3465E4E105F285E23AB8788412827E4F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PaymentsOfDividends" xlink:label="loc_us-gaap_PaymentsOfDividends_70B38BE4FAFB11704402788412824F2B" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_PaymentsOfDividends_70B38BE4FAFB11704402788412824F2B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_D1519909E53928C6EC8A788412836739" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesBasic_D1519909E53928C6EC8A788412836739" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted" xlink:label="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted_DE5FD0119F13E79CD95578841283AD66" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_UndistributedEarningsLossAllocatedToParticipatingSecuritiesDiluted_DE5FD0119F13E79CD95578841283AD66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_561ECEBB1036CC5E083678841283081A" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicLineItems_B6BEA9E95DD79CA1F5127884127A0BEB" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_561ECEBB1036CC5E083678841283081A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EarningsPerShareTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlans" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_91DB8FB28E0AA335D58378928ACE5B0B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_91DB8FB28E0AA335D58378928ACE5B0B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanNameAxis" xlink:label="loc_us-gaap_RetirementPlanNameAxis_4055ADB7FD4AAF6C7D5C78928ACF7FD7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_91DB8FB28E0AA335D58378928ACE5B0B" xlink:to="loc_us-gaap_RetirementPlanNameAxis_4055ADB7FD4AAF6C7D5C78928ACF7FD7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_2F8B643860138FF9F95C78928ACF9794_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanNameAxis_4055ADB7FD4AAF6C7D5C78928ACF7FD7" xlink:to="loc_us-gaap_RetirementPlanNameDomain_2F8B643860138FF9F95C78928ACF9794_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanNameDomain" xlink:label="loc_us-gaap_RetirementPlanNameDomain_2F8B643860138FF9F95C78928ACF9794" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanNameAxis_4055ADB7FD4AAF6C7D5C78928ACF7FD7" xlink:to="loc_us-gaap_RetirementPlanNameDomain_2F8B643860138FF9F95C78928ACF9794" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_OfficerMedicalPlanMember" xlink:label="loc_bah_OfficerMedicalPlanMember_9BCCF45A94573D7349FE78928ACFB67E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanNameDomain_2F8B643860138FF9F95C78928ACF9794" xlink:to="loc_bah_OfficerMedicalPlanMember_9BCCF45A94573D7349FE78928ACFB67E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_C083903118B78B799DB678928AD0F5F8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_91DB8FB28E0AA335D58378928ACE5B0B" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_C083903118B78B799DB678928AD0F5F8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_D9AA76CB6CA9FE16216A78928AD0D745_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_C083903118B78B799DB678928AD0F5F8" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_D9AA76CB6CA9FE16216A78928AD0D745_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_D9AA76CB6CA9FE16216A78928AD0D745" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_C083903118B78B799DB678928AD0F5F8" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_D9AA76CB6CA9FE16216A78928AD0D745" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember" xlink:label="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_A1174CCC3146C7D8B1EA78928AD0BF5A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_D9AA76CB6CA9FE16216A78928AD0D745" xlink:to="loc_us-gaap_SupplementalEmployeeRetirementPlanDefinedBenefitMember_A1174CCC3146C7D8B1EA78928AD0BF5A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_FD96A0EB55F107F068AF78928AD08F21" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_D9AA76CB6CA9FE16216A78928AD0D745" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_FD96A0EB55F107F068AF78928AD08F21" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount" xlink:label="loc_bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount_A002FB32AC7FD1895DF378928AD19453" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_bah_DeferredCompensationArrangementWithIndividualAnnualCashAwardGrantedPerYearOfServiceAmount_A002FB32AC7FD1895DF378928AD19453" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_AB019AF3340EC7AE6F3578928AD101AA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_AB019AF3340EC7AE6F3578928AD101AA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_7268A3565DFAF2CA971578928AD1B79C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_7268A3565DFAF2CA971578928AD1B79C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01ECBEBBAFA9F13CC6E178928AD14C9A" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_01ECBEBBAFA9F13CC6E178928AD14C9A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_A2AA71E21250FC96C2AE78928AD21144" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_A2AA71E21250FC96C2AE78928AD21144" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PostemploymentBenefitsLiabilityNoncurrent" xlink:label="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_4F60241F3848E86EC7D378928AD27D58" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_PostemploymentBenefitsLiabilityNoncurrent_4F60241F3848E86EC7D378928AD27D58" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage" xlink:label="loc_bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage_181B9A716FA55685E09478928AD2C697" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_bah_DeferredCompensationPlansMaximumEligibleDeferralofCompensationPercentage_181B9A716FA55685E09478928AD2C697" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationPlanAssets" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_62623899E016D988A0D978928AD24A4C" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_62623899E016D988A0D978928AD24A4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_FB93C25A85F7E2322EEF78928AD2C3FE" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_08CE925D81CAADA0B66678928AD0D02A" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_FB93C25A85F7E2322EEF78928AD2C3FE" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/EmployeeBenefitPlansTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurements" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_891F87544F85E1B540CF54A21D94E7C7" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_18783811743D63F17EDA54A21D908AB5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_891F87544F85E1B540CF54A21D94E7C7" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_18783811743D63F17EDA54A21D908AB5" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByLiabilityClassAxis" xlink:label="loc_us-gaap_FairValueByLiabilityClassAxis_E6460178CD4A11615CBB54A21D909804" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_18783811743D63F17EDA54A21D908AB5" xlink:to="loc_us-gaap_FairValueByLiabilityClassAxis_E6460178CD4A11615CBB54A21D909804" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_DB7B9B83C38BA58F575F54A21D918E28_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_E6460178CD4A11615CBB54A21D909804" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_DB7B9B83C38BA58F575F54A21D918E28_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_DB7B9B83C38BA58F575F54A21D918E28" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByLiabilityClassAxis_E6460178CD4A11615CBB54A21D909804" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_DB7B9B83C38BA58F575F54A21D918E28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_4A1D519D4CD7B5B1067E54A21D91B59B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationByLiabilityClassDomain_DB7B9B83C38BA58F575F54A21D918E28" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_4A1D519D4CD7B5B1067E54A21D91B59B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1AD56B8F44BD2E273B1254A21D925F9E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_18783811743D63F17EDA54A21D908AB5" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1AD56B8F44BD2E273B1254A21D925F9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_F27DC21D8394CCA467A754A21D92504C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1AD56B8F44BD2E273B1254A21D925F9E" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_F27DC21D8394CCA467A754A21D92504C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_F27DC21D8394CCA467A754A21D92504C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1AD56B8F44BD2E273B1254A21D925F9E" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_F27DC21D8394CCA467A754A21D92504C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_3E0EB81A65EBB1A0750354A21D92BAFF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_F27DC21D8394CCA467A754A21D92504C" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_3E0EB81A65EBB1A0750354A21D92BAFF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2F71D8BD58296324563654A21D936426" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_18783811743D63F17EDA54A21D908AB5" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2F71D8BD58296324563654A21D936426" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2F71D8BD58296324563654A21D936426" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_2F71D8BD58296324563654A21D936426" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_E8629480DD79922E7F9554A21D9402FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_E8629480DD79922E7F9554A21D9402FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_7853CC7AF84D99B05D7154A21D9428B9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_7853CC7AF84D99B05D7154A21D9428B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_8D67413CEEAAEA6AE41554A21D94E55E" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_76A387127F473E83695654A21D931414" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_8D67413CEEAAEA6AE41554A21D94E55E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AssetsFairValueDisclosureAbstract" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_6C69456DC2ABCB54253B54A21D95A0D9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_891F87544F85E1B540CF54A21D94E7C7" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_6C69456DC2ABCB54253B54A21D95A0D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationPlanAssets" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_D751930AA0E6050CB57554A21D95A440" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_6C69456DC2ABCB54253B54A21D95A0D9" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_D751930AA0E6050CB57554A21D95A440" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherAssetsFairValueDisclosure" xlink:label="loc_us-gaap_OtherAssetsFairValueDisclosure_0F15899D5AF009551BE254A21D952B4B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_6C69456DC2ABCB54253B54A21D95A0D9" xlink:to="loc_us-gaap_OtherAssetsFairValueDisclosure_0F15899D5AF009551BE254A21D952B4B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_891F87544F85E1B540CF54A21D94E7C7" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_0C068EF3E65128FAE46D54A21D9A6A11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityNoncurrent_0C068EF3E65128FAE46D54A21D9A6A11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_CE9032F04047870F070454A21D9A0893" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_CE9032F04047870F070454A21D9A0893" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_BE5EACD39AF55E9A7F7654A21D9A0310" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_BE5EACD39AF55E9A7F7654A21D9A0310" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_6EB634EC16CD98C7632F54A21D9A0000" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_6EB634EC16CD98C7632F54A21D9A0000" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_D0B35138CCC20E856C0654A21D9BE7D6" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_1B1BA03392D4ABB14ECF54A21D9903CA" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_D0B35138CCC20E856C0654A21D9BE7D6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/FairValueMeasurementsTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwardsLineItems" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingLossCarryforwardsTable" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_AD9E78ABDEB0EC1A7655788AA89E2C43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_AD9E78ABDEB0EC1A7655788AA89E2C43" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxPeriodAxis" xlink:label="loc_us-gaap_TaxPeriodAxis_44272BCDEB03A469D02D788AA89F7F3E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_AD9E78ABDEB0EC1A7655788AA89E2C43" xlink:to="loc_us-gaap_TaxPeriodAxis_44272BCDEB03A469D02D788AA89F7F3E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:label="loc_us-gaap_TaxPeriodDomain_E6469A7B195897D83387788AA89F24E8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxPeriodAxis_44272BCDEB03A469D02D788AA89F7F3E" xlink:to="loc_us-gaap_TaxPeriodDomain_E6469A7B195897D83387788AA89F24E8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TaxPeriodDomain" xlink:label="loc_us-gaap_TaxPeriodDomain_E6469A7B195897D83387788AA89F24E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxPeriodAxis_44272BCDEB03A469D02D788AA89F7F3E" xlink:to="loc_us-gaap_TaxPeriodDomain_E6469A7B195897D83387788AA89F24E8" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TaxYears20132015Member" xlink:label="loc_bah_TaxYears20132015Member_23D98637812F9A3B12E4788AA89F95C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_E6469A7B195897D83387788AA89F24E8" xlink:to="loc_bah_TaxYears20132015Member_23D98637812F9A3B12E4788AA89F95C5" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_TaxYears20162021Member" xlink:label="loc_bah_TaxYears20162021Member_BFFE519C3A66E9CAE631788AA89F6C52" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxPeriodDomain_E6469A7B195897D83387788AA89F24E8" xlink:to="loc_bah_TaxYears20162021Member_BFFE519C3A66E9CAE631788AA89F6C52" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_73BF01D9E935F077FF65788AA8A087F5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_73BF01D9E935F077FF65788AA8A087F5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_92B47EE17B2265630FBA788AA8A05FD8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_92B47EE17B2265630FBA788AA8A05FD8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss" xlink:label="loc_us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss_840351B8710B80656663788AA8A08533" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_us-gaap_IncomeTaxExaminationEstimateOfPossibleLoss_840351B8710B80656663788AA8A08533" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LiabilityForUncertainTaxPositionsNoncurrent" xlink:label="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_D8631525E58EDB84A746788AA8A052D4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_us-gaap_LiabilityForUncertainTaxPositionsNoncurrent_D8631525E58EDB84A746788AA8A052D4" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_LiabilityForUncertaintyInIncomeTaxesNoncurrentResearchAndDevelopmentTaxCredits" xlink:label="loc_bah_LiabilityForUncertaintyInIncomeTaxesNoncurrentResearchAndDevelopmentTaxCredits_11979D7E8D5C05E453457896FEC1E809" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_bah_LiabilityForUncertaintyInIncomeTaxesNoncurrentResearchAndDevelopmentTaxCredits_11979D7E8D5C05E453457896FEC1E809" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_LiabilityForUncertaintyInIncomeTaxesNoncurrentAcquisitions" xlink:label="loc_bah_LiabilityForUncertaintyInIncomeTaxesNoncurrentAcquisitions_B5789FADB760797016B47897976E4D4D" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_B93941FDE9BACC115E1D788AA8A09B51" xlink:to="loc_bah_LiabilityForUncertaintyInIncomeTaxesNoncurrentAcquisitions_B5789FADB760797016B47897976E4D4D" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Leases" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/LeasesMinimumFutureObligationsForOperatingLeasesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/LeasesScheduleOfLeaseCostDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/LeasesSupplementalCashFlowAndOtherInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/LeasesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilities" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/OtherLongTermLiabilitiesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RelatedPartyTransactions" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_1DB0FB525015514A8D1F9E462352D3A5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_25BF867DFCE55B0285700E9D7CFA72E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_1DB0FB525015514A8D1F9E462352D3A5" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_25BF867DFCE55B0285700E9D7CFA72E0" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_5C409F9C3C5752F6B924EE70FDA48388" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_25BF867DFCE55B0285700E9D7CFA72E0" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_5C409F9C3C5752F6B924EE70FDA48388" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_BB021E28AEF67B08488D213D9BCDF2B8_F50AF4BEE34E5972A056910DDAEDAFA8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_5C409F9C3C5752F6B924EE70FDA48388" xlink:to="loc_us-gaap_RelatedPartyDomain_BB021E28AEF67B08488D213D9BCDF2B8_F50AF4BEE34E5972A056910DDAEDAFA8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaap_RelatedPartyDomain_048DB75F848D5D3FB03EA00B054B58AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_5C409F9C3C5752F6B924EE70FDA48388" xlink:to="loc_us-gaap_RelatedPartyDomain_048DB75F848D5D3FB03EA00B054B58AE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_AffiliatedEntityMember" xlink:label="loc_srt_AffiliatedEntityMember_30C98613FD365DC2BDB222E84D97C036" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_048DB75F848D5D3FB03EA00B054B58AE" xlink:to="loc_srt_AffiliatedEntityMember_30C98613FD365DC2BDB222E84D97C036" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_B54BFE3D25285EE7A7A9591E5C9A211D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_25BF867DFCE55B0285700E9D7CFA72E0" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_B54BFE3D25285EE7A7A9591E5C9A211D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_C5438F108AD7BE673950213D9BCE75E1_F50AF4BEE34E5972A056910DDAEDAFA8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_B54BFE3D25285EE7A7A9591E5C9A211D" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_C5438F108AD7BE673950213D9BCE75E1_F50AF4BEE34E5972A056910DDAEDAFA8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_13BA6110669857D58645EF2C30F16DBF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_B54BFE3D25285EE7A7A9591E5C9A211D" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_13BA6110669857D58645EF2C30F16DBF" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_ServicesPerformedUnderSubcontractorMember" xlink:label="loc_bah_ServicesPerformedUnderSubcontractorMember_52F5A51943A35C5A8A23FB9D41933D7F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_13BA6110669857D58645EF2C30F16DBF" xlink:to="loc_bah_ServicesPerformedUnderSubcontractorMember_52F5A51943A35C5A8A23FB9D41933D7F" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_NumberofDirectors" xlink:label="loc_bah_NumberofDirectors_1550F07E7FE95150A09D48BE29FAF941" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_1DB0FB525015514A8D1F9E462352D3A5" xlink:to="loc_bah_NumberofDirectors_1550F07E7FE95150A09D48BE29FAF941" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_0C13FE29F39358F6B2899FC018454D5B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_1DB0FB525015514A8D1F9E462352D3A5" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_0C13FE29F39358F6B2899FC018454D5B" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/Revenue" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17139E135E47F6E53D495DD20DE61820" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2DC7C78813A3C97C59F85DD20DE540BA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17139E135E47F6E53D495DD20DE61820" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2DC7C78813A3C97C59F85DD20DE540BA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_35CF4660318D4BE077AE5DD20DE549E2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_2DC7C78813A3C97C59F85DD20DE540BA" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_35CF4660318D4BE077AE5DD20DE549E2" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodOne" xlink:label="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodOne_AEA2A8D0C5396B56679E5DD20DE6BC80" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17139E135E47F6E53D495DD20DE61820" xlink:to="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodOne_AEA2A8D0C5396B56679E5DD20DE6BC80" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodTwo" xlink:label="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodTwo_002BE85A1800399E7ED95DD20DE698D4" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17139E135E47F6E53D495DD20DE61820" xlink:to="loc_bah_RevenueRemainingPerformanceObligationExpectedTimingofSatisfactionPeriodTwo_002BE85A1800399E7ED95DD20DE698D4" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueScheduleOfContractAssetsAndLiabilitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueSchedulesOfDisaggregationOfRevenueDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_C164098274645801B2F760CA463210BE" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_6C6CB77675025B5085BE3ABCB8885D4F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_C164098274645801B2F760CA463210BE" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_6C6CB77675025B5085BE3ABCB8885D4F" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_2E5527BA1F6D5DCAB793AF7A20BA3F6C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6C6CB77675025B5085BE3ABCB8885D4F" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_2E5527BA1F6D5DCAB793AF7A20BA3F6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_004A988D61EB199D548FE6B1AA3BB59B_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_2E5527BA1F6D5DCAB793AF7A20BA3F6C" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_004A988D61EB199D548FE6B1AA3BB59B_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_4E4D7AABFAB65C95A089634DFFB0043E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_2E5527BA1F6D5DCAB793AF7A20BA3F6C" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_4E4D7AABFAB65C95A089634DFFB0043E" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_CostReimbursableContractMember" xlink:label="loc_bah_CostReimbursableContractMember_6647C1165C325AF9889F514638B8BFAD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_4E4D7AABFAB65C95A089634DFFB0043E" xlink:to="loc_bah_CostReimbursableContractMember_6647C1165C325AF9889F514638B8BFAD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TimeAndMaterialsContractMember" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_E8DF459DAEEC595AB8710720EC69AD8A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_4E4D7AABFAB65C95A089634DFFB0043E" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_E8DF459DAEEC595AB8710720EC69AD8A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FixedPriceContractMember" xlink:label="loc_us-gaap_FixedPriceContractMember_AC6E5B96C4475CAAA2AB29B161AE10F4" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_4E4D7AABFAB65C95A089634DFFB0043E" xlink:to="loc_us-gaap_FixedPriceContractMember_AC6E5B96C4475CAAA2AB29B161AE10F4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MajorCustomersAxis" xlink:label="loc_srt_MajorCustomersAxis_EBF9210CC5FC5A308BDDBA1E97875DBF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6C6CB77675025B5085BE3ABCB8885D4F" xlink:to="loc_srt_MajorCustomersAxis_EBF9210CC5FC5A308BDDBA1E97875DBF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_4AD1301D5497D805FF33E6B1AA3CA9C0_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_EBF9210CC5FC5A308BDDBA1E97875DBF" xlink:to="loc_srt_NameOfMajorCustomerDomain_4AD1301D5497D805FF33E6B1AA3CA9C0_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_E3EA98AF7AAF574CB8EAD3E8340F5CD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_EBF9210CC5FC5A308BDDBA1E97875DBF" xlink:to="loc_srt_NameOfMajorCustomerDomain_E3EA98AF7AAF574CB8EAD3E8340F5CD9" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_DefenseClientsMember" xlink:label="loc_bah_DefenseClientsMember_46DCB065748A5EA68C64096D20CFE7C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E3EA98AF7AAF574CB8EAD3E8340F5CD9" xlink:to="loc_bah_DefenseClientsMember_46DCB065748A5EA68C64096D20CFE7C2" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_IntelligenceClientsMember" xlink:label="loc_bah_IntelligenceClientsMember_2707B20094FB5F06A2D41C2B2CA39C7A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E3EA98AF7AAF574CB8EAD3E8340F5CD9" xlink:to="loc_bah_IntelligenceClientsMember_2707B20094FB5F06A2D41C2B2CA39C7A" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_CivilClientsMember" xlink:label="loc_bah_CivilClientsMember_7994C16613085F5DAABC39BA3DFB17C1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E3EA98AF7AAF574CB8EAD3E8340F5CD9" xlink:to="loc_bah_CivilClientsMember_7994C16613085F5DAABC39BA3DFB17C1" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_GlobalCommercialClientsMember" xlink:label="loc_bah_GlobalCommercialClientsMember_F2591DB6254E59F4A58816C28AB479DD" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_E3EA98AF7AAF574CB8EAD3E8340F5CD9" xlink:to="loc_bah_GlobalCommercialClientsMember_F2591DB6254E59F4A58816C28AB479DD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_22307496533A5EFD8FA7A429220E6DC2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6C6CB77675025B5085BE3ABCB8885D4F" xlink:to="loc_srt_StatementGeographicalAxis_22307496533A5EFD8FA7A429220E6DC2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_C9472226DFB2A9C3D72DE6B1AA3D4B8F_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_22307496533A5EFD8FA7A429220E6DC2" xlink:to="loc_srt_SegmentGeographicalDomain_C9472226DFB2A9C3D72DE6B1AA3D4B8F_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_6891AE7DE426586C80E757798C93108C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_22307496533A5EFD8FA7A429220E6DC2" xlink:to="loc_srt_SegmentGeographicalDomain_6891AE7DE426586C80E757798C93108C" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_AB27FBAEEC0954DAA2AD9C0F40171F96" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_6891AE7DE426586C80E757798C93108C" xlink:to="loc_country_US_AB27FBAEEC0954DAA2AD9C0F40171F96" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelAxis" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3134E0EB4C2C5CD6AFC07D29071F1862" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_6C6CB77675025B5085BE3ABCB8885D4F" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3134E0EB4C2C5CD6AFC07D29071F1862" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_057502B5298CA7F161CFE6B1AA3EAD0F_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3134E0EB4C2C5CD6AFC07D29071F1862" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_057502B5298CA7F161CFE6B1AA3EAD0F_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerSalesChannelDomain" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1277796263D75BF29F8E1317F123E817" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_3134E0EB4C2C5CD6AFC07D29071F1862" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1277796263D75BF29F8E1317F123E817" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SalesChannelDirectlyToConsumerMember" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_C0495CCFB89A5A49864175A801A67515" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1277796263D75BF29F8E1317F123E817" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_C0495CCFB89A5A49864175A801A67515" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SalesChannelThroughIntermediaryMember" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_1EF3D23491B45615BEC9C5337266B30F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_1277796263D75BF29F8E1317F123E817" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_1EF3D23491B45615BEC9C5337266B30F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_F4A9FB9624325D36AA22EE356D3D453A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_C164098274645801B2F760CA463210BE" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_F4A9FB9624325D36AA22EE356D3D453A" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage" xlink:label="loc_bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage_C155744973D25043955CBAF552F50D84" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_C164098274645801B2F760CA463210BE" xlink:to="loc_bah_RevenueFromContractWithCustomerExcludingAssessedTaxPercentage_C155744973D25043955CBAF552F50D84" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/RevenueTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensation" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationScheduleOfStockBasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_FB680930EB2857D0A80F9F3081B793A5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_786165D02B2151BF9019569191CE387B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_FB680930EB2857D0A80F9F3081B793A5" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_786165D02B2151BF9019569191CE387B" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_5472A27DD34352E38FC90263D41F4F66" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_786165D02B2151BF9019569191CE387B" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_5472A27DD34352E38FC90263D41F4F66" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_BEAF6C446CF399F38DAFE6B1A8D1A1C2_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5472A27DD34352E38FC90263D41F4F66" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_BEAF6C446CF399F38DAFE6B1A8D1A1C2_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_8EF7328C637D518F8687349B07F5C81E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_5472A27DD34352E38FC90263D41F4F66" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_8EF7328C637D518F8687349B07F5C81E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfSalesMember" xlink:label="loc_us-gaap_CostOfSalesMember_58F07F1CF07E5A6196DDE9A265232E34" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_8EF7328C637D518F8687349B07F5C81E" xlink:to="loc_us-gaap_CostOfSalesMember_58F07F1CF07E5A6196DDE9A265232E34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_1C6515F05CBB5C4CBE2AA172F3C77E58" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_8EF7328C637D518F8687349B07F5C81E" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_1C6515F05CBB5C4CBE2AA172F3C77E58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_EBF97CE50B6E5A2DB60767D24E3D7DB3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_786165D02B2151BF9019569191CE387B" xlink:to="loc_us-gaap_AwardTypeAxis_EBF97CE50B6E5A2DB60767D24E3D7DB3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_830E1194722490DCEAACE6B1A8D2924A_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_EBF97CE50B6E5A2DB60767D24E3D7DB3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_830E1194722490DCEAACE6B1A8D2924A_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_637F90CAA2775CC9B4CFD6DA720B047D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_EBF97CE50B6E5A2DB60767D24E3D7DB3" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_637F90CAA2775CC9B4CFD6DA720B047D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_0AC6D75C51815B98824FEB90E46BC245" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_637F90CAA2775CC9B4CFD6DA720B047D" xlink:to="loc_us-gaap_EmployeeStockOptionMember_0AC6D75C51815B98824FEB90E46BC245" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_B618D0501B465604BED5BCE46EB19B79" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_637F90CAA2775CC9B4CFD6DA720B047D" xlink:to="loc_us-gaap_RestrictedStockMember_B618D0501B465604BED5BCE46EB19B79" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_6C97971EB4EF556EB1DF9561E4941C29" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_786165D02B2151BF9019569191CE387B" xlink:to="loc_us-gaap_PlanNameAxis_6C97971EB4EF556EB1DF9561E4941C29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_78EAD247B85832D7DE21E6B1A8D33A5A_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_6C97971EB4EF556EB1DF9561E4941C29" xlink:to="loc_us-gaap_PlanNameDomain_78EAD247B85832D7DE21E6B1A8D33A5A_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_1918B4BED2FE5955A743980B12C4D6AE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_6C97971EB4EF556EB1DF9561E4941C29" xlink:to="loc_us-gaap_PlanNameDomain_1918B4BED2FE5955A743980B12C4D6AE" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_AB44021396635CA3B356CE77EDC53B0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1918B4BED2FE5955A743980B12C4D6AE" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_AB44021396635CA3B356CE77EDC53B0A" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AnnualIncentivePlanMember" xlink:label="loc_bah_AnnualIncentivePlanMember_D90BA9CE8AA05E5D849E72BB8201E5B0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_1918B4BED2FE5955A743980B12C4D6AE" xlink:to="loc_bah_AnnualIncentivePlanMember_D90BA9CE8AA05E5D849E72BB8201E5B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_9E2F3B49AEFB5AF8A7255C24A798CFF4" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_786165D02B2151BF9019569191CE387B" xlink:to="loc_us-gaap_StatementClassOfStockAxis_9E2F3B49AEFB5AF8A7255C24A798CFF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_6C5E3A7272C027CA14DEE6B1A8D4C5B0_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9E2F3B49AEFB5AF8A7255C24A798CFF4" xlink:to="loc_us-gaap_ClassOfStockDomain_6C5E3A7272C027CA14DEE6B1A8D4C5B0_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_7E3061421A5A53A184EC49B6A9B6ED16" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_9E2F3B49AEFB5AF8A7255C24A798CFF4" xlink:to="loc_us-gaap_ClassOfStockDomain_7E3061421A5A53A184EC49B6A9B6ED16" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_FB9F234E51B157BDB353A3947C9108D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_7E3061421A5A53A184EC49B6A9B6ED16" xlink:to="loc_us-gaap_CommonClassAMember_FB9F234E51B157BDB353A3947C9108D4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_F388F38022B25A5BBAD3D2A66B503D52" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_FB680930EB2857D0A80F9F3081B793A5" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_F388F38022B25A5BBAD3D2A66B503D52" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationStockPlansDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DCA4CAC83AC7276F61FA54A0E6387798" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DCA4CAC83AC7276F61FA54A0E6387798" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_C4003C79550B7194E67954A0E63FD674" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DCA4CAC83AC7276F61FA54A0E6387798" xlink:to="loc_srt_RangeAxis_C4003C79550B7194E67954A0E63FD674" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_7010A46C5287CE7AD34F54A0E63F3758_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_C4003C79550B7194E67954A0E63FD674" xlink:to="loc_srt_RangeMember_7010A46C5287CE7AD34F54A0E63F3758_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_7010A46C5287CE7AD34F54A0E63F3758" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_C4003C79550B7194E67954A0E63FD674" xlink:to="loc_srt_RangeMember_7010A46C5287CE7AD34F54A0E63F3758" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_2D7AD5DF6A93B720B95154A0E63F0E4D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7010A46C5287CE7AD34F54A0E63F3758" xlink:to="loc_srt_MinimumMember_2D7AD5DF6A93B720B95154A0E63F0E4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_9AF685FFA39D65078D8054A0E640261B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7010A46C5287CE7AD34F54A0E63F3758" xlink:to="loc_srt_MaximumMember_9AF685FFA39D65078D8054A0E640261B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_8B7AC1A195597364FE4954A0E6409A8F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DCA4CAC83AC7276F61FA54A0E6387798" xlink:to="loc_us-gaap_StatementClassOfStockAxis_8B7AC1A195597364FE4954A0E6409A8F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_C116FC17A0A9BAA81F7C54A0E640F092_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8B7AC1A195597364FE4954A0E6409A8F" xlink:to="loc_us-gaap_ClassOfStockDomain_C116FC17A0A9BAA81F7C54A0E640F092_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_C116FC17A0A9BAA81F7C54A0E640F092" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_8B7AC1A195597364FE4954A0E6409A8F" xlink:to="loc_us-gaap_ClassOfStockDomain_C116FC17A0A9BAA81F7C54A0E640F092" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_F264ED604D173AD68D4354A0E640B85E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_C116FC17A0A9BAA81F7C54A0E640F092" xlink:to="loc_us-gaap_CommonClassAMember_F264ED604D173AD68D4354A0E640B85E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_2516B7F991A765B3D3AE54A0E641CDAF" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DCA4CAC83AC7276F61FA54A0E6387798" xlink:to="loc_us-gaap_AwardTypeAxis_2516B7F991A765B3D3AE54A0E641CDAF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3D21B4B5835227AB730954A0E641B3C2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_2516B7F991A765B3D3AE54A0E641CDAF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3D21B4B5835227AB730954A0E641B3C2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3D21B4B5835227AB730954A0E641B3C2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_2516B7F991A765B3D3AE54A0E641CDAF" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3D21B4B5835227AB730954A0E641B3C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_526F5FB5CD26517CA62A54A0E641034C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3D21B4B5835227AB730954A0E641B3C2" xlink:to="loc_us-gaap_EmployeeStockOptionMember_526F5FB5CD26517CA62A54A0E641034C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_0B4541F8CCB891F17E6454A0E641B215" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_3D21B4B5835227AB730954A0E641B3C2" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_0B4541F8CCB891F17E6454A0E641B215" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_F0900223E717B33DC3D954A0E6427987" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_DCA4CAC83AC7276F61FA54A0E6387798" xlink:to="loc_us-gaap_PlanNameAxis_F0900223E717B33DC3D954A0E6427987" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_0C73F47C086DFC23F2B754A0E642DAB8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_F0900223E717B33DC3D954A0E6427987" xlink:to="loc_us-gaap_PlanNameDomain_0C73F47C086DFC23F2B754A0E642DAB8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_0C73F47C086DFC23F2B754A0E642DAB8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_F0900223E717B33DC3D954A0E6427987" xlink:to="loc_us-gaap_PlanNameDomain_0C73F47C086DFC23F2B754A0E642DAB8" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_A845DDBBF6D6AEA3502D54A0E64282C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_0C73F47C086DFC23F2B754A0E642DAB8" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_A845DDBBF6D6AEA3502D54A0E64282C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_7884EDDBB041654AA5C354A0E6423EB3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_7884EDDBB041654AA5C354A0E6423EB3" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue" xlink:label="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_BF01B68702C7C97462FC54A0E6436BFC" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_bah_ShareBasedCompensationArrangementbyShareBasedPaymentAwardOptionsGrantsinPeriodGrantDateFairValue_BF01B68702C7C97462FC54A0E6436BFC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_BDA51FD1AAA91A912F0C54A0E643F73D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_BDA51FD1AAA91A912F0C54A0E643F73D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_2632C69E8DE00BA5DE1D54A0E643940F" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_2632C69E8DE00BA5DE1D54A0E643940F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_5DF4FB0B0CE9997DF29954A0E6439F1A" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares_5DF4FB0B0CE9997DF29954A0E6439F1A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_392D6CA7DD68BE33A63F54A0E6437B35" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_392D6CA7DD68BE33A63F54A0E6437B35" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantsinPeriodFairValue" xlink:label="loc_bah_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantsinPeriodFairValue_A1C879E67A1AC508C83854A0E6449C5C" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_bah_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsGrantsinPeriodFairValue_A1C879E67A1AC508C83854A0E6449C5C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaap_SharePrice_97CE71FAF78005A8F7F854A0E64493C2" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_SharePrice_97CE71FAF78005A8F7F854A0E64493C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockSharesAcquired" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_DA6B87C43762AD8A133554A0E6448C0A" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_DA6B87C43762AD8A133554A0E6448C0A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_52E06E89D94BB557F0B054A0E644D9BA" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_52E06E89D94BB557F0B054A0E644D9BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_FDBE5308A12E6929024754A0E6442925" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_42E5AE178A3FAF61B66B54A0E642809D" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_FDBE5308A12E6929024754A0E6442925" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.boozallen.com/role/StockBasedCompensationUnrecognizedCompensationDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E9182DB1C595CD6AABB9653726DF816" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_08DBBD772969589096AA21163792D2F3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E9182DB1C595CD6AABB9653726DF816" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_08DBBD772969589096AA21163792D2F3" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaap_PlanNameAxis_ECCCA7A1DBB85D7399E0C28BF0B5781D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_08DBBD772969589096AA21163792D2F3" xlink:to="loc_us-gaap_PlanNameAxis_ECCCA7A1DBB85D7399E0C28BF0B5781D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_F293C713C6EE77EAA552E6B1A8893AF6_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_ECCCA7A1DBB85D7399E0C28BF0B5781D" xlink:to="loc_us-gaap_PlanNameDomain_F293C713C6EE77EAA552E6B1A8893AF6_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaap_PlanNameDomain_B826956A25C75AF2803063AF27BFEF65" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_ECCCA7A1DBB85D7399E0C28BF0B5781D" xlink:to="loc_us-gaap_PlanNameDomain_B826956A25C75AF2803063AF27BFEF65" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AmendedAndRestatedEquityIncentivePlanMember" xlink:label="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_6A931416C8895EC48E6FA793FC2C2DA9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_B826956A25C75AF2803063AF27BFEF65" xlink:to="loc_bah_AmendedAndRestatedEquityIncentivePlanMember_6A931416C8895EC48E6FA793FC2C2DA9" xlink:type="arc" />
    <link:loc xlink:href="bah-20200630.xsd#bah_AnnualIncentivePlanMember" xlink:label="loc_bah_AnnualIncentivePlanMember_2B1D749225215C6D9E2CDEEEF513433A" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_B826956A25C75AF2803063AF27BFEF65" xlink:to="loc_bah_AnnualIncentivePlanMember_2B1D749225215C6D9E2CDEEEF513433A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_B29AC7A769785514AB917B74CE3B0C08" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_08DBBD772969589096AA21163792D2F3" xlink:to="loc_us-gaap_AwardTypeAxis_B29AC7A769785514AB917B74CE3B0C08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2FFAC4152ED83DF6D29AE6B1A88AB692_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_B29AC7A769785514AB917B74CE3B0C08" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_2FFAC4152ED83DF6D29AE6B1A88AB692_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F3E4A97479975ADA95366C6AC6FE96D8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_B29AC7A769785514AB917B74CE3B0C08" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F3E4A97479975ADA95366C6AC6FE96D8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:label="loc_us-gaap_EmployeeStockOptionMember_478988B3EA9058F1B8930AB6CBB14D68" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F3E4A97479975ADA95366C6AC6FE96D8" xlink:to="loc_us-gaap_EmployeeStockOptionMember_478988B3EA9058F1B8930AB6CBB14D68" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaap_RestrictedStockMember_9D7A39FDC80C52C8B62E5788CA6ABC28" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_F3E4A97479975ADA95366C6AC6FE96D8" xlink:to="loc_us-gaap_RestrictedStockMember_9D7A39FDC80C52C8B62E5788CA6ABC28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_1E27A0433F30569E886F18505EC60A2C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_08DBBD772969589096AA21163792D2F3" xlink:to="loc_us-gaap_StatementClassOfStockAxis_1E27A0433F30569E886F18505EC60A2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_1D4794B6506BCAB92F6DE6B1A88B942D_D385608E73B55C9CBF33F6074D842F11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1E27A0433F30569E886F18505EC60A2C" xlink:to="loc_us-gaap_ClassOfStockDomain_1D4794B6506BCAB92F6DE6B1A88B942D_D385608E73B55C9CBF33F6074D842F11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_12A59028FF925039AC1F76AE3FB7336A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_1E27A0433F30569E886F18505EC60A2C" xlink:to="loc_us-gaap_ClassOfStockDomain_12A59028FF925039AC1F76AE3FB7336A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonClassAMember" xlink:label="loc_us-gaap_CommonClassAMember_EA2F0ECC313A511F9938CE7B4E77D21C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_12A59028FF925039AC1F76AE3FB7336A" xlink:to="loc_us-gaap_CommonClassAMember_EA2F0ECC313A511F9938CE7B4E77D21C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_F59342E604965EBC8D1217563CA1B723" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E9182DB1C595CD6AABB9653726DF816" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_F59342E604965EBC8D1217563CA1B723" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_8A8AB69510D85068B52DCBA5FB103C47" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4E9182DB1C595CD6AABB9653726DF816" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_8A8AB69510D85068B52DCBA5FB103C47" xlink:type="arc" />
  </link:definitionLink>
</link:linkbase>
