The Collaborative International Dictionary of English v.0.48:

Dioecia \Di*[oe]"ci*a\ (d[-i]*[=e]"sh[i^]*[.a]), n. pl. [NL.,
   fr. Gr. di = di`s twice + o'i^kos a house.]
   1. (Bot.) A Linn[ae]an class of plants having the stamens and
      pistils on different plants.
      [1913 Webster]

   2. (Zool.) A subclass of gastropod mollusks in which the
      sexes are separate. It includes most of the large marine
      species, like the conchs, cones, and cowries. Dioecian