The Collaborative International Dictionary of English v.0.48:

Unsociable \Unsociable\
   See sociable.

The Collaborative International Dictionary of English v.0.48:

Unsociable \Un*so"cia*ble\, a.
   Not sociable; not inclined to society; averse to
   companionship or conversation; solitary; reserved; as, an
   unsociable person or temper. -- Un*so"cia*ble*ness, n. --
   Un*so"cia*bly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

unsociable
    adj 1: not inclined to society or companionship; "an unsociable
           nature...shy and reserved"; "generally unsociable except
           with intimate friends"; "unsociable behavior"; "an
           unsociable neighborhood" [ant: sociable]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "unsociable":
   Timonistic, aloof, antisocial, autistic, bashful, chill, chilly,
   close, cold, cool, cynical, disaccordant,
   disinclined to communicate, dissociable, distant, frosty, icy,
   incompatible, inhospitable, inimical, insociable, man-hating,
   meaningless, misogynous, mopey, mopish, morose, nongregarious,
   offish, reserved, secretive, self-contained, self-sufficient,
   sexist, shut-in, snug, socially incompatible, solitary, standoff,
   standoffish, strained, sullen, tense, timid, unamiable, unamicable,
   unclubbable, uncommunicative, uncompanionable, uncongenial,
   unconversable, uncordial, unfriendly, ungenial, unharmonious,
   unsocial, woman-hating