The Collaborative International Dictionary of English v.0.48:

outmoded \outmoded\ adj.
   1. same as old-fashioned, a., 3.

   Syn: antique, demode, old-fashioned[3], old-hat(predicate),
        out-of-date, out of fashion(predicate), out of
        style(predicate), passe, passee.
        [WordNet 1.5]

   2. Unacceptable because it is inferior to current standards,
      procedures, or technology.

   Syn: obsolete, outdated, out-of-date, superannuated,
        old-fashioned[2].
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

outmoded
    adj 1: out of fashion; "a suit of rather antique appearance";
           "demode (or outmoded) attire"; "outmoded ideas" [syn:
           antique, demode, ex, old-fashioned, old-hat(p),
           outmoded, passe, passee]

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "outmoded":
   abandoned, abjured, antiquated, antique, archaic, back-number,
   behind the times, dated, dead, demode, deserted, discontinued,
   disused, done with, extinct, frumpy, 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   out of use, out-of-date, outdated, outworn, passe, past use,
   pensioned off, relinquished, renounced, resigned, retired, stodgy,
   styleless, superannuate, superannuated, superseded, unfashionable,
   vintage, worn-out