The Collaborative International Dictionary of English v.0.48:

Heteronymous \Het`er*on"y*mous\, a. [Hetero- + Gr. "o`nyma, for
   "o`noma a name.]
   Having different names or designations; standing in opposite
   relations. --J. Le Conte. -- Het"er*on"y*mous*ly, adv.
   [1913 Webster]