Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

pessimistic
     adj : expecting the worst in this worst of all possible worlds
           [ant: {optimistic}]