anisogamy

from WordNet (r) 3.0 (2006)

anisogamy
    n 1: (biology) reproduction by the union or fusion of two
         differing gametes (especially differing in size)

from The Collaborative International Dictionary of English v.0.48

anisogamy \anisogamy\ n.
   1. (biology) reproduction by the union or fusion of two
      differing gametes (especially differing in size).
      [WordNet 1.5] Anisol