thirster

from WordNet (r) 3.0 (2006)

thirster
    n 1: a person with a strong desire for something; "a longer for
         money"; "a thirster after blood"; "a yearner for knowledge"
         [syn: {longer}, {thirster}, {yearner}]

from The Collaborative International Dictionary of English v.0.48

Thirster \Thirst"er\, n.
   One who thirsts.
   [1913 Webster]