The Collaborative International Dictionary of English v.0.48:

Outdated \Out*dat"ed\, a.
   Being out of date; antiquated; outmoded; unfashionable.
   [Obs.] --Hammond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

outdated
    adj 1: old; no longer valid or fashionable; "obsolete words";
           "an obsolete locomotive"; "outdated equipment";
           "superannuated laws"; "out-of-date ideas" [syn:
           outdated, out-of-date, superannuated]

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "outdated":
   abandoned, abjured, antiquated, antique, archaic, back-number,
   behind the times, dated, deserted, discontinued, disused,
   done with, has-been, not worth saving, obsolescent, obsolete, old,
   old hat, old-fashioned, old-timey, oldfangled, on the shelf, out,
   out of fashion, out of season, out of use, out-of-date, outmoded,
   outworn, past use, pensioned off, relinquished, renounced,
   resigned, retired, styleless, superannuate, superannuated,
   superseded, unfashionable, worn-out