"drunken revelry," 1630s, from the name of the Roman festival held in honor of Bacchus, from neuter plural of Latin bacchanalis "having to do with Bacchus" (q.v.); the festivals became so notorious for excess that they were forbidden by the Senate 186 B.C.E. A participant is a Bacchant (1690s), fem. Bacchante, from French. The plural of both is Bacchantes.