WordNet (r) 3.0 (2006):

fantasize
    v 1: indulge in fantasies; "he is fantasizing when he says he
         plans to start his own company" [syn: fantasy,
         fantasize, fantasise]
    2: portray in the mind; "he is fantasizing the ideal wife" [syn:
       fantasize, fantasise]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "fantasize":
   coin, conceit, conceive, conceptualize, concoct, cook up,
   counterfeit, create, dream, dream up, envisage, envision,
   experience imaginatively, fabricate, fake, fancy, fictionalize,
   forge, fudge, hallucinate, hatch, hoke up, ideate, imagine, invent,
   make up, manufacture, mold, mull over, muse, originate, produce,
   shape, speculate, suppose, think up, trump up