The Collaborative International Dictionary of English v.0.48:

Requisition \Req`ui*si"tion\ (r?k`w?-z?sh"?n), n.[Cf. F.
   r['e]quisition, L. requisitio a searching.]
   1. The act of requiring, as of right; a demand or application
      made as by authority. Specifically:
      (a) (International Law) A formal demand made by one state
          or government upon another for the surrender or
          extradition of a fugitive from justice. --Kent.
      (b) (Law) A notarial demand of a debt. --Wharton.
      (c) (Mil.) A demand by the invader upon the people of an
          invaded country for supplies, as of provision, forage,
          transportation, etc. --Farrow.
      (d) A formal application by one officer to another for
          things needed in the public service; as, a requisition
          for clothing, troops, or money.
          [1913 Webster]

   2. That which is required by authority; especially, a quota
      of supplies or necessaries.
      [1913 Webster]

   3. A written or normal call; an invitation; a summons; as, a
      reqisition for a public meeting. [Eng.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Requisition \Req`ui*si"tion\, v. t.
   1. To make a reqisition on or for; as, to requisition a
      district for forage; to requisition troops.
      [1913 Webster]

   2. To present a requisition to; to summon request; as, to
      requisition a person to be a candidate. [Eng.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

requisition
    n 1: the act of requiring; an authoritative request or demand,
         especially by a military or public authority that takes
         something over (usually temporarily) for military or public
         use
    2: an official form on which a request in made; "first you have
       to fill out the requisition" [syn: requisition,
       requisition form]
    3: seizing property that belongs to someone else and holding it
       until profits pay the demand for which it was seized [syn:
       sequestration, requisition]
    v 1: make a formal request for official services
    2: demand and take for use or service, especially by military or
       public authority for public service [ant: derequisition]

Moby Thesaurus II by Grady Ward, 1.0:

174 Moby Thesaurus words for "requisition":
   address, adopt, adoption, application, apply for, appropriate,
   appropriation, arrogate, arrogation, ask, ask for, asking, assume,
   assumption, authorization, authorize, bare necessities, beck,
   beck and call, beg leave, bespeak, bid come, bidding, blackmail,
   call, call away, call back, call for, call forth, call in,
   call out, call together, call up, calling, calling forth,
   challenge, cite, claim, clamor for, colonization, colonize,
   commandeer, confiscate, conjure, conjure up, conquer, conquest,
   contribution, convene, convocation, convoke, crave, cry for,
   demand, demand for, desideration, desideratum, desire, draft,
   drain, duty, enslave, enslavement, essential, essentials,
   evocation, evoke, exact, exaction, expressed desire, expropriate,
   extort, extortion, extortionate demand, file for, heavy demand,
   hog, impetration, impose, imposition, impost, indent,
   indispensable, insistent demand, invocation, invoke,
   issue an ultimatum, jump a claim, levy, make a demand,
   make a request, make a requisition, make application,
   make free with, make use of, mandate, monopolize, must, must item,
   muster, muster up, necessaries, necessities, necessity, need,
   need for, nod, nonnegotiable demand, notice, occasion, occupation,
   occupy, order, order up, overrun, page, petition, place an order,
   postulate, preconization, preconize, preempt, preemption,
   preoccupation, preoccupy, prepossess, prepossession,
   prerequirement, prerequisite, put in for, put in requisition,
   recall, request, require, requirement, requisite, rush, rush order,
   screw, seize, send after, send for, serve, sit on, solicit,
   squat on, subjugate, subjugation, subpoena, summon, summon forth,
   summon up, summons, take all of, take it all, take over,
   take possession of, take up, takeover, taking over, tax, taxing,
   the necessary, the needful, tribute, ultimatum, usurp, usurpation,
   voucher, want, warn, warning, whistle for, wish