The Collaborative International Dictionary of English v.0.48:

Unfashionable \Unfashionable\
   See fashionable.

WordNet (r) 3.0 (2006):

unfashionable
    adj 1: not in accord with or not following current fashion;
           "unfashionable clothes"; "melodrama of a now
           unfashionable kind" [syn: unfashionable, unstylish]
           [ant: fashionable, stylish]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "unfashionable":
   Bohemian, back-number, beat, behind the times, breakaway, dated,
   far out, free and easy, fringy, has-been, heretical, heterodox,
   hippie, informal, kinky, maverick, not cricket, not done,
   not kosher, offbeat, old hat, old-fashioned, old-timey, oldfangled,
   original, out of fashion, out of season, out-of-date, outdated,
   outmoded, styleless, unconventional, unorthodox, way out