Why is the ninth month called September?
c.1300, "fight with a spear or lance on horseback with another knight; tilt in a tournament," from Old French joster "to joust, tilt," from Vulgar Latin *iuxtare "to approach, come together, meet," originally "be next to," from Latin iuxta "beside, near," related to iungere "join together" (see jugular). Formerly spelled, and until modern times pronounced, "just." Related: Jousted; jousting.
c.1300, from Old French joustes, from joster (see joust (v.)). The sport was popular with Anglo-Norman knights.
These early tournaments were very rough affairs, in every sense, quite unlike the chivalrous contests of later days; the rival parties fought in groups, and it was considered not only fair but commendable to hold off until you saw some of your adversaries getting tired and then to join in the attack on them; the object was not to break a lance in the most approved style, but frankly to disable as many opponents as possible for the sake of obtaining their horses, arms, and ransoms. [L.F. Salzman, "English Life in the Middle Ages," Oxford, 1950]