The Collaborative International Dictionary of English v.0.48:

Contingent \Con*tin"gent\, a. [L. contingens, -entis, p. pr. of
   contingere to touch on all sides, to happen; con- + tangere
   to touch: cf. F. contingent. See Tangent, Tact.]
   1. Possible, or liable, but not certain, to occur;
      incidental; casual.
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            Weighing so much actual crime against so much
            contingent advantage.                 --Burke.
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   2. Dependent on that which is undetermined or unknown; as,
      the success of his undertaking is contingent upon events
      which he can not control. "Uncertain and contingent
      causes." --Tillotson.
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   3. (Law) Dependent for effect on something that may or may
      not occur; as, a contingent estate.
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            If a contingent legacy be left to any one when he
            attains, or if he attains, the age of twenty-one.
                                                  --Blackstone.
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The Collaborative International Dictionary of English v.0.48:

Contingent \Con*tin"gent\, n.
   1. An event which may or may not happen; that which is
      unforeseen, undetermined, or dependent on something
      future; a contingency.
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            His understanding could almost pierce into future
            contingents.                          --South.
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   2. That which falls to one in a division or apportionment
      among a number; a suitable share; proportion; esp., a
      quota of troops.
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            From the Alps to the border of Flanders, contingents
            were required . . . 200,000 men were in arms.
                                                  --Milman.
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WordNet (r) 3.0 (2006):

contingent
    adj 1: possible but not certain to occur; "they had to plan for
           contingent expenses"
    2: determined by conditions or circumstances that follow; "arms
       sales contingent on the approval of congress" [syn:
       contingent, contingent on(p), contingent upon(p),
       dependent on(p), dependant on(p), dependent upon(p),
       dependant upon(p), depending on(p)]
    3: uncertain because of uncontrollable circumstances; "the
       results of confession were not contingent, they were
       certain"- George Eliot
    n 1: a gathering of persons representative of some larger group;
         "each nation sent a contingent of athletes to the Olympics"
    2: a temporary military unit; "the peacekeeping force includes
       one British contingent" [syn: contingent, detail]