Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

unsociableness
     n : an unsociable disposition; avoiding friendship or
         companionship [syn: {unsociability}] [ant: {sociability}]