From 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]
From 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]