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.
      [1913 Webster]

            Weighing so much actual crime against so much
            contingent advantage.                 --Burke.
      [1913 Webster]

   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.
      [1913 Webster]

   3. (Law) Dependent for effect on something that may or may
      not occur; as, a contingent estate.
      [1913 Webster]

            If a contingent legacy be left to any one when he
            attains, or if he attains, the age of twenty-one.
                                                  --Blackstone.
      [1913 Webster]

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.
      [1913 Webster]

            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.
      [1913 Webster]

            From the Alps to the border of Flanders, contingents
            were required . . . 200,000 men were in arms.
                                                  --Milman.
      [1913 Webster]

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]

Moby Thesaurus II by Grady Ward, 1.0:

257 Moby Thesaurus words for "contingent":
   accessory, accident, accidental, addendum, addition, additional,
   adjunct, adscititious, adventitious, adventure, age group,
   aleatory, allotment, allowance, appendage, appurtenance,
   appurtenant, ascititious, at issue, auxiliary, band, based on,
   battalion, bevy, big end, bigger half, bit, bite, body, boxed in,
   brigade, brushing, budget, bunch, cabal, cast, casual, casualty,
   causeless, chance, chance hit, chancy, chunk, circumscribed by,
   circumstantial, clique, cogitable, cohort, collateral, coming,
   coming to be, commission, company, complement, component,
   conceivable, conceivably possible, conditional, conditioned,
   contacting, contingency, contingent on, corps, coterie, covey,
   crew, cross section, crowd, cut, deal, dependent, dependent on,
   depending, depending on, depending on circumstances, destinal,
   destiny, detachment, detail, dicey, dividend, division, dole, end,
   equal share, event, eventual, eventuality, eventuation, extra,
   faction, fatal, fate, fatidic, final, fleet, fluke, fluky,
   fortuitous, fortuity, fraction, freak accident, gang, glancing,
   grazing, group, grouping, groupment, half, halver, hap, happening,
   happenstance, hazard, hedged about by, helping, hinging on,
   humanly possible, iffy, imaginable, impingent, impinging,
   in contact, in question, in suspense, in the balance, in-group,
   incidence, incident to, incidental, incidental to, indeterminate,
   indirect, inessential, installment, interest, item, junta, last,
   likely, long odds, long shot, lot, lucky shot, materialization,
   measure, meed, meeting, mere chance, mess, mob, modicum, moiety,
   movement, nonessential, not-self, nudging, occasional, odd, open,
   osculatory, other, out-group, outfit, pack, parcel, part,
   particular, party, peer group, pendent, pending, percentage,
   phalanx, piece, platoon, plausible, portion, posse, possible,
   potential, predicated on, probable, proportion, provisional,
   quadrant, quantum, quarter, quota, rake-off, random sample, ration,
   realization, regiment, relative, reliant, remainder, revolving on,
   risky, rubbing, salon, sample, sampling, secondary, section,
   sector, segment, set, share, slice, small share, squad, stable,
   stake, steady, stock, string, subdivision, subgroup, subject to,
   subsidiary, subspecies, superadded, superaddition, superfluous,
   supervenient, supplement, supplemental, supplementary, suspenseful,
   tangent, tangential, team, thinkable, touching, tribe, troop,
   troupe, turning on, ultimate, unanticipated, uncaused, uncounted,
   undecided, undetermined, unessential, unestablished, unexpected,
   unfixed, unforeseeable, unforeseen, unlooked-for, unpredictable,
   unsettled, untold, up for grabs, wing



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CONTINGENT. What may or may not happen;. what depends upon a doubtful event;
as, a contingent debt, which is a debt depending upon some uncertain event.
9 Ves. It. 110; Co. Bankr. Laws, 245; 7 Ves. It. 301; 1 Ves. & Bea. 176; 8
Ves. R. 334; 1 Rose, R. 523; 3 T. R. 539; 4 T. R. 570. A contingent legacy
is one which is not vested. Will. on Executors, h.t. See Contingent
Remainder; Contingent Use.