The Collaborative International Dictionary of English v.0.48:
Pessimist \Pes"si*mist\, Pessimistic \Pes`si*mis"tic\, a. (Metaph.) Of or pertaining to pessimism; characterized by pessimism; gloomy; foreboding. "Giving utterance to pessimistic doubt." --Encyc. Brit. [1913 Webster]WordNet (r) 3.0 (2006):
pessimistic adj 1: expecting the worst possible outcome [ant: optimistic]