The Collaborative International Dictionary of English v.0.48:

Joust \Joust\ (joust or j[u^]st; 277), v. i. [OE. justen,
   jousten, OF. jouster, jouster, joster, F. jouter, fr. L.
   juxta near to, nigh, from the root of jungere to join. See
   Join, and cf. Jostle.]
   1. To engage in mock combat on horseback, as two knights in
      the lists; to tilt. [Written also just.]
      [1913 Webster +PJC]

            For the whole army to joust and tourney. --Holland.
      [1913 Webster]

   2. Hence: To engage in a competition involving one-to-one
      struggle with an opponent.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Joust \Joust\, n. [OE. juste, jouste, OF. juste, jouste, joste,
   F. joute. See Joust, v. i.]
   1. A tilting match; a mock combat on horseback between two
      knights in the lists or inclosed field. [Written also
      just.]
      [1913 Webster]

            Gorgeous knights at joust and tournament. --Milton.
      [1913 Webster]

   2. Hence: Any competition involving one-to-one struggle with
      an opponent.
      [PJC]

WordNet (r) 3.0 (2006):

joust
    n 1: a combat between two mounted knights tilting against each
         other with blunted lances [syn: joust, tilt]
    v 1: joust against somebody in a tournament by fighting on
         horseback

Moby Thesaurus II by Grady Ward, 1.0:

61 Moby Thesaurus words for "joust":
   Olympic games, Olympics, battle, bout, box, brawl, broil, clash,
   close, collide, combat, come to blows, concours, contend, contest,
   cut and thrust, derby, duel, encounter, engagement, exchange blows,
   fence, feud, fight, fight a duel, game, games, give and take,
   give satisfaction, go, grapple, grapple with, gymkhana, jostle,
   match, matching, meet, meeting, mix it up, quarrel, rally, rassle,
   rencontre, riot, run a tilt, scramble, scuffle, skirmish, spar,
   strive, struggle, test, thrust and parry, tilt, tournament,
   tourney, trial, tussle, wage war, war, wrestle