Bacchus,
From The Oxford Companion to Beer
the Roman god of wine, is otherwise known as Dionysius to the Greeks. He is more traditionally associated with wine, the vine and grapes as well as being the inducer of madness and ecstasy; this frenzy is known to the Romans as bakkheia. Though Bacchus is one of the 12 Olympians, it is generally understood that he was an outsider and not of classical Greek origin. He is one of Zeus’s sons and considered by Silenus, the Greek God of Beer and Drinking, to be his mentor. Indeed, since Silenus is not part of the Roman pantheon of gods, Bacchus assumes some of the attributes of his drinking companion. Bacchus, along with King Gambrinus and other historical or mythological figures associated with drinking, has often been depicted in classical beer art and advertising.
This definition is from The Oxford Companion to Beer, edited by Garrett Oliver. © Oxford University Press 2012.