The Collaborative International Dictionary of English v.0.48:

Unscientific \Unscientific\
   See scientific.

WordNet (r) 3.0 (2006):

unscientific
    adj 1: not consistent with the methods or principles of science;
           "an unscientific lack of objectivity" [ant: scientific]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "unscientific":
   absonant, contradictory, contrary to reason, fallacious, faulty,
   flawed, illogical, inauthentic, inconclusive, incongruous,
   inconsequent, inconsequential, inconsistent, invalid, irrational,
   loose, nonscientific, not following, paralogical, reasonless,
   self-annulling, self-contradictory, self-refuting, senseless,
   unauthentic, unconnected, unphilosophical, unreasonable,
   without reason