Source : Webster's Revised Unabridged Dictionary (1913)

Guzzler \Guz"zler\ (-zl[~e]r), n.
   An immoderate drinker.

Source : WordNet®

guzzler
     n 1: someone who drinks heavily (especially alcoholic beverages);
          "he's a beer guzzler every night"
     2: a drinker who swallows large amounts greedily [syn: {gulper}]