The Collaborative International Dictionary of English v.0.48:

Homogeny \Ho*mog"e*ny\, n. [Gr. ?; ? the same + ? race, kind.]
   1. Joint nature. [Obs.] --Bacon.
      [1913 Webster]

   2. (Biol.) The correspondence of common descent; -- a term
      used to supersede homology by Lankester, who also used
      homoplasy to denote any superinduced correspondence of
      position and structure in parts embryonically distinct
      (other writers using the term homoplasmy). Thus, there is
      homogeny between the fore limb of a mammal and the wing of
      a bird; but the right and left ventricles of the heart in
      both are only in homoplasy with each other, these having
      arisen independently since the divergence of both groups
      from a univentricular ancestor.
      [1913 Webster]

WordNet (r) 3.0 (2006):

homogeny
    n 1: (biology) similarity because of common evolution