The Collaborative International Dictionary of English v.0.48:

Premonition \Pre`mo*ni"tion\, n. [L. praemonitio. See
   Premonish.]
   Previous warning, notice, or information; forewarning; as, a
   premonition of danger.
   [1913 Webster]

WordNet (r) 3.0 (2006):

premonition
    n 1: a feeling of evil to come; "a steadily escalating sense of
         foreboding"; "the lawyer had a presentiment that the judge
         would dismiss the case" [syn: foreboding, premonition,
         presentiment, boding]
    2: an early warning about a future event [syn: forewarning,
       premonition]

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "premonition":
   ESP, advance notice, apprehensiveness, clairsentience,
   clairvoyance, extrasensory perception, feeling, foreboding,
   forefeeling, foresight, forewarning, funny feeling, hunch,
   impression, insight, intimation, intuition, intuitive impression,
   lucidity, misgiving, plenty of notice, portent, preapprehension,
   precautioning, prediction, prenotice, prenotification, prenotion,
   presage, presagement, presentiment, prewarning, psychometry,
   second sight, sixth sense, sneaking suspicion, suspicion,
   vague feeling, vague idea