The Collaborative International Dictionary of English v.0.48:

Unsocial \Unsocial\
   See social.

WordNet (r) 3.0 (2006):

unsocial
    adj 1: not seeking or given to association; being or living
           without companions; "the unsocial disposition to neglect
           one's neighbors" [ant: social]

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "unsocial":
   aloof, anchoretic, anchoritic, antisocial, autistic, bashful,
   chilly, close, cold, cool, detached, dissociable, distant,
   hermitical, hostile, incompatible, inhospitable, insociable,
   misanthropic, mopey, mopish, morose, nongregarious, reclusive,
   reserved, retiring, self-contained, self-sufficient, snug,
   socially incompatible, solitary, standoffish, sullen, unamiable,
   unclubbable, uncommunicative, uncompanionable, uncongenial,
   unfriendly, ungenial, unsociable, withdrawn