The Collaborative International Dictionary of English v.0.48:

Mismate \Mis*mate"\, v. t.
   To mate wrongly or unsuitably; to mismatch; as, to mismate
   gloves or shoes; a mismated couple.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mismate
    v 1: provide with an unsuitable mate