The Collaborative International Dictionary of English v.0.48:

Contention \Con*ten"tion\, n. [F. contention, L. contentio. See
   Contend.]
   1. A violent effort or struggle to obtain, or to resist,
      something; contest; strife.
      [1913 Webster]

            I would my arms could match thee in contention.
                                                  --Shak.
      [1913 Webster]

   2. Strife in words; controversy; altercation; quarrel;
      dispute; as, a bone of contention.
      [1913 Webster]

            Contentions and strivings about the law. --Titus
                                                  iii. 9.
      [1913 Webster]

   3. Vehemence of endeavor; eagerness; ardor; zeal.
      [1913 Webster]

            An end . . . worthy our utmost contention to obtain.
                                                  --Rogers.
      [1913 Webster]

   4. A point maintained in an argument, or a line of argument
      taken in its support; the subject matter of discussion or
      strife; a position taken or contended for.
      [1913 Webster]

            All men seem agreed what is to be done; the
            contention is how the subject is to be divided and
            defined.                              --Bagehot.
      [1913 Webster]

            This was my original contention, and I still
            maintain that you should abide by your former
            decision.                             --Jowett.

   Syn: Struggle; strife; contest; quarrel; combat; conflict;
        feud; litigation; controversy; dissension; variance;
        disagreement; debate; competition; emulation.

   Usage: Contention, Strife. A struggle between two parties
          is the idea common to these two words. Strife is a
          struggle for mastery; contention is a struggle for the
          possession of some desired object, or the
          accomplishment of some favorite end. Neither of the
          words is necessarily used in a bad sense, since there
          may be a generous strife or contention between two
          friends as to which shall incur danger or submit to
          sacrifices. Ordinarily, however, these words denote a
          struggle arising from bad passions. In that case,
          strife usually springs from a quarrelsome temper, and
          contention from, a selfish spirit which seeks its own
          aggrandizement, or is fearful lest others should
          obtain too much. Strife has more reference to the
          manner than to the object of a struggle, while
          contention takes more account of the end to be gained.
          [1913 Webster]

WordNet (r) 3.0 (2006):

contention
    n 1: a point asserted as part of an argument
    2: a contentious speech act; a dispute where there is strong
       disagreement; "they were involved in a violent argument"
       [syn: controversy, contention, contestation,
       disputation, disceptation, tilt, argument, arguing]
    3: the act of competing as for profit or a prize; "the teams
       were in fierce contention for first place" [syn:
       competition, contention, rivalry] [ant: cooperation]

Moby Thesaurus II by Grady Ward, 1.0:

167 Moby Thesaurus words for "contention":
   Discordia, Eris, altercation, antagonism, anteposition, antipathy,
   antithesis, apologetics, apologia, apology, argument,
   argumentation, argumentative, bellicose, belligerence, belligerent,
   bicker, bickering, blood feud, brawl, broil, bucking, captious,
   carping, casuistry, caviling, challenge, clash, clashing,
   collision, combative, conflict, confrontation, confrontment,
   contentious, contestation, contradiction, contraposition,
   contrariety, contrary, contrast, contravention, contraversion,
   controversial, controversy, counteraction, counterworking,
   crosscurrent, crossing, defense, denial, despitefulness,
   difference, disaccord, disaffinity, discord, discordance,
   discordancy, disharmony, disputation, disputatious, dispute,
   dissension, dissent, dissidence, disunity, donnybrook,
   donnybrook fair, embroilment, enmity, faultfinding, feud, fiery,
   fight, fliting, flyting, fracas, friction, froward, fuss, hassle,
   hasty, hate, hatred, head wind, hostility, hotheaded, hubbub,
   hurrah, imbroglio, impetuous, impugnation, impugnment,
   incompatibility, incompatibleness, inharmoniousness, inharmony,
   jangle, jar, litigation, litigious, logomachy, malevolence, malice,
   malignity, militant, mischief, negation, noncooperation,
   open conflict, open quarrel, opposing, opposition, opposure,
   oppugnation, paper war, passage of arms, peppery, perverse,
   polar opposition, polarity, polarization, polemic, polemical,
   polemics, posing against, pugnacious, quarrel, quarrelsome,
   quarrelsomeness, rebutment, rebuttal, refusal, rejection,
   repugnance, resistance, rhubarb, rub, rumpus, scrappy, set-to,
   sharp words, slanging match, snarl, spat, spite, spitefulness,
   squabble, standing against, strained relations, strife, tension,
   tiff, traversal, truculent, tussle, undercurrent, unharmoniousness,
   unpleasantness, variance, vendetta, verbal engagement,
   war of words, warlike, words, wrangle, wrangling