1560s, "characterized by intemperate drinking;" see Bacchanalia + -an. From 1620s as "pertaining to Bacchanals." As a noun from 1610s, "participant in the Bacchanalia."
Entries linking to bacchanalian
Bacchanalia n.
"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.
-an
word-forming element meaning "pertaining to," from Latin -anus, adjective suffix, in some cases via French -ain, -en. From PIE *-no-.