The Collaborative International Dictionary of English v.0.48:

Contest \Con*test"\, v. t. [imp. & p. p. Contested; p. pr. &
   vb. n. Contesting.] [F. contester, fr. L. contestari to
   call to witness, contestari litem to introduce a lawsuit by
   calling witnesses, to bring an action; con- + testari to be a
   witness, testic witness. See Testify.]
   1. To make a subject of dispute, contention, litigation, or
      emulation; to contend for; to call in question; to
      controvert; to oppose; to dispute.
      [1913 Webster]

            The people . . . contested not what was done.
                                                  --Locke.
      [1913 Webster]

            Few philosophical aphorisms have been more frequenty
            repeated, few more contested than this. --J. D.
                                                  Morell.
      [1913 Webster]

   2. To strive earnestly to hold or maintain; to struggle to
      defend; as, the troops contested every inch of ground.
      [1913 Webster]

   3. (Law) To make a subject of litigation; to defend, as a
      suit; to dispute or resist; as a claim, by course of law;
      to controvert.
      [1913 Webster]

   To contest an election. (Polit.)
      (a) To strive to be elected.
      (b) To dispute the declared result of an election.

   Syn: To dispute; controvert; debate; litigate; oppose; argue;
        contend.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Contest \Con*test"\, v. i.
   To engage in contention, or emulation; to contend; to strive;
   to vie; to emulate; -- followed usually by with.
   [1913 Webster]

         The difficulty of an argument adds to the pleasure of
         contesting with it, when there are hopes of victory.
                                                  --Bp. Burnet.
   [1913 Webster]

         Of man, who dares in pomp with Jove contest? --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Contest \Con"test\, n.
   1. Earnest dispute; strife in argument; controversy; debate;
      altercation.
      [1913 Webster]

            Leave all noisy contests, all immodest clamors and
            brawling language.                    --I. Watts.
      [1913 Webster]

   2. Earnest struggle for superiority, victory, defense, etc.;
      competition; emulation; strife in arms; conflict; combat;
      encounter.
      [1913 Webster]

            The late battle had, in effect, been a contest
            between one usurper and another.      --Hallam.
      [1913 Webster]

            It was fully expected that the contest there would
            be long and fierce.                   --Macaulay.

   Syn: Conflict; combat; battle; encounter; shock; struggle;
        dispute; altercation; debate; controvesy; difference;
        disagreement; strife.

   Usage: Contest, Conflict, Combat, Encounter. Contest
          is the broadest term, and had originally no reference
          to actual fighting. It was, on the contrary, a legal
          term signifying to call witnesses, and hence came to
          denote first a struggle in argument, and then a
          struggle for some common object between opposing
          parties, usually one of considerable duration, and
          implying successive stages or acts. Conflict denotes
          literally a close personal engagement, in which sense
          it is applied to actual fighting. It is, however, more
          commonly used in a figurative sense to denote
          strenuous or direct opposition; as, a mental conflict;
          conflicting interests or passions; a conflict of laws.
          An encounter is a direct meeting face to face. Usually
          it is a hostile meeting, and is then very nearly
          coincident with conflict; as, an encounter of opposing
          hosts. Sometimes it is used in a looser sense; as,
          "this keen encounter of our wits." --Shak. Combat is
          commonly applied to actual fighting, but may be used
          figuratively in reference to a strife or words or a
          struggle of feeling.
          [1913 Webster]

WordNet (r) 3.0 (2006):

contest
    n 1: an occasion on which a winner is selected from among two or
         more contestants [syn: contest, competition]
    2: a struggle between rivals
    v 1: to make the subject of dispute, contention, or litigation;
         "They contested the outcome of the race" [syn: contest,
         contend, repugn]

Moby Thesaurus II by Grady Ward, 1.0:

233 Moby Thesaurus words for "contest":
   Kilkenny cats, Olympic games, Olympics, abjure, action,
   altercation, antagonize, argue, argufy, argument,
   assert the contrary, awake a doubt, bandy words, battle,
   be contrary to, be diffident, be doubtful, be dubious,
   be skeptical, be uncertain, beat against, beat up against, belie,
   bicker, bicker over, bickering, bout, box, brawl, breast the wave,
   broil, brush, buck, buffet, buffet the waves, call in question,
   call into question, cat-and-dog life, cavil, challenge,
   championship, choplogic, clash, close, close with, collide, combat,
   come to blows, compete with, competition, concours, conflict,
   confute, contend, contend about, contend against, contention,
   contentiousness, contestation, contradict, contravene, controversy,
   controvert, counter, cross, cross swords, cut and thrust, debate,
   decathlon, deny, derby, disaffirm, disallow, disavow, discept,
   disclaim, disown, disprove, disputation, dispute, distrust,
   double-header, doubles, doubt, duel, emulation, encounter,
   engagement, enmity, event, exchange blows, fence, feud, fight,
   fight a duel, fight against, fight over, fighting, forswear,
   foursome, gainsay, game, games, games of chance, give and take,
   give satisfaction, go, grapple, grapple with,
   greet with skepticism, gymkhana, half believe, harbor suspicions,
   hassle, have it out, have reservations, hostility, impugn,
   join battle with, join issue, join issue upon, jostle, joust,
   labor against, litigation, lock horns, logomachize, logomachy,
   match, matching, meet, meeting, militate against, misgive,
   mistrust, mix it up, moot, negate, not accept, not admit, nullify,
   object to, offer resistance, oppose, oppugn, paper war, pentathlon,
   pettifog, play, play-off, plead, polemic, polemicize, polemize,
   proving, quarrel, quarrel over, quarreling, quarrelsomeness, query,
   question, quibble, race, raise a question, rally, rassle, rebut,
   recant, refuse to admit, refute, reject, reluct, reluctate,
   rencontre, renounce, repudiate, retract, revoke, riot, rival,
   rivalry, run a tilt, runoff, scramble, scrapping, scruple, scuffle,
   singles, skirmish, smell a rat, spar, sport, squabble over,
   squabbling, stem the tide, strife, strive, strive against,
   striving, struggle, struggle against, suspect, take back,
   take issue with, take on, take sides, test, testing, thrash out,
   threesome, throw doubt upon, thrust and parry, tilt, tournament,
   tourney, traverse, treat with reserve, trial, try conclusions,
   trying, tug-of-war, tussle, twosome, vie with, wage war, war,
   war of words, warfare, words, wrangle, wrangle over, wrangling,
   wrestle