Source : Webster's Revised Unabridged Dictionary (1913)

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

         Gorgeous knights at joust and tournament. --Milton.

Joust \Joust\, 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}.]
   To engage in mock combat on horseback, as two knights in the
   lists; to tilt. [Written also {just}.]

         For the whole army to joust and tourney. --Holland.

Source : WordNet®

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