Source : Webster's Revised Unabridged Dictionary (1913)

Dissimilarity \Dis*sim`i*lar"i*ty\, n.
   Want of resemblance; unlikeness; dissimilitude; variety; as,
   the dissimilarity of human faces and forms. --Sir W. Jones.

Source : WordNet®

dissimilarity
     n : the quality of being dissimilar [syn: {unsimilarity}] [ant:
         {similarity}]