The Collaborative International Dictionary of English v.0.48:

Masticate \Mas"ti*cate\, v. t. [imp. & p. p. Masticated; p.
   pr. & vb. n. Masticating.] [L. masticatus, p. p. of
   masticare to chew, prob. fr. mastiche mastic. See Mastic.]
   To grind or crush with, or as with, the teeth and prepare for
   swallowing and digestion; to chew; as, to masticate food.
   [1913 Webster]

WordNet (r) 3.0 (2006):

masticate
    v 1: grind and knead; "masticate rubber"
    2: chew (food); to bite and grind with the teeth; "He jawed his
       bubble gum"; "Chew your food and don't swallow it!"; "The
       cows were masticating the grass" [syn: chew, masticate,
       manducate, jaw]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "masticate":
   bite, bruise, champ, chaw, chew, chew the cud, chew up, chomp,
   chump, crunch, crush, gnash, gnaw, grind, gum, macerate, mash,
   mouth, mumble, munch, nibble, pulp, pulpify, ruminate, scrunch,
   smash, squash