The Collaborative International Dictionary of English v.0.48:
Imbiber \Im*bib"er\, n. One who, or that which, imbibes. [1913 Webster]WordNet (r) 3.0 (2006):
imbiber n 1: a person who drinks alcoholic beverages (especially to excess) [syn: drinker, imbiber, toper, juicer] [ant: abstainer, abstinent, nondrinker]