The Collaborative International Dictionary of English v.0.48:

Contradistinguish \Con`tra*dis*tin"guish\ (?; 144), v. t. [imp.
   & p. p. Contradistinguished; p. pr. & vb. n.
   Contradistinguishing.]
   To distinguish by a contrast of opposite qualities.
   [1913 Webster]

         These are our complex ideas of soul and body, as
         contradistinguished.                     --Locke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

contradistinguish
    v 1: distinguish by contrasting qualities