The Collaborative International Dictionary of English v.0.48:

Dipsomaniac \Dip`so*ma"ni*ac\, n.
   One who has an irrepressible desire for alcoholic drinks.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dipsomaniac
    n 1: a person who drinks alcohol to excess habitually [syn:
         alcoholic, alky, dipsomaniac, boozer, lush,
         soaker, souse]

Moby Thesaurus II by Grady Ward, 1.0:

68 Moby Thesaurus words for "dipsomaniac":
   LSD user, acidhead, addict, alcoholic, alcoholic addict, bacchanal,
   bacchanalian, bibber, big drunk, boozer, carouser, chain smoker,
   chronic alcoholic, chronic drunk, cocaine sniffer, cokie, cubehead,
   devotee of Bacchus, dope fiend, doper, drinker, drug abuser,
   drug addict, drug user, drunk, drunkard, fiend, freak,
   glue sniffer, guzzler, habitual, hard drinker, head, heavy drinker,
   heavy smoker, hophead, hype, imbiber, inebriate, junkie, lovepot,
   marijuana smoker, methhead, narcotics addict, oenophilist,
   pathological drinker, pillhead, pot companion, pothead,
   problem drinker, reveler, serious drinker, shikker, snowbird,
   soaker, social drinker, sot, speed freak, swigger, swiller,
   thirsty soul, tippler, toper, tosspot, tripper, user, wassailer,
   winebibber