The Collaborative International Dictionary of English v.0.48:

Unclothed \Un*clothed"\, a.
   1. [Properly p. p. of unclothe.] Divested or stripped of
      clothing. --Byron.
      [1913 Webster]

   2. [Pref. un- not + clothed.] Not yet clothed; wanting
      clothes; naked.
      [1913 Webster] -- Un*cloth"ed*ly, adv. [Obs.] --Bacon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

unclothed
    adj 1: not wearing clothing [ant: clad, clothed]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "unclothed":
   clothesless, decollete, disrobed, en deshabille, garbless,
   garmentless, half-clothed, in dishabille, low-cut, naked, nude,
   nudish, raimentless, raw, stark-naked, strapless, stripped,
   topless, unattired, uncased, unclad, undraped, undressed, ungarbed,
   ungarmented, unrobed