The Collaborative International Dictionary of English v.0.48:

fress \fress\ v. i. [Yiddish, fresn fr. G. fressen to eat (used
   of animals).]
   to eat copiously and without restraint; to snack frequently.
   [slang]

   Syn: gluttonize.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

fress
    v 1: eat a lot and without restraint [syn: gluttonize,
         gluttonise, fress]