The Collaborative International Dictionary of English v.0.48:

Bacchus \Bac"chus\, n. [L., fr. Gr. Ba`kchos.] (Myth.)
   The god of wine, son of Jupiter and Semele.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Bacchus
    n 1: (classical mythology) god of wine; equivalent of Dionysus

The Devil's Dictionary (1881-1906):

BACCHUS, n.  A convenient deity invented by the ancients as an excuse
for getting drunk.

    Is public worship, then, a sin,
        That for devotions paid to Bacchus
    The lictors dare to run us in,
        And resolutely thump and whack us?
                                                                Jorace