Source : Webster's Revised Unabridged Dictionary (1913)

Oospere \O"["o]*spere\, n. [Gr. ? an egg + E. sphere.]
   1. (Bot.) An unfertilized, rounded mass of protoplasm,
      produced in an o["o]gonium.

   Note: After being fertilized by the access of antherozoids it
         becomes covered with a cell wall and develops into an
         o["o]spore, which may grow into a new plant like the
         parent.

   2. (Bot.) An analogous mass of protoplasm in the ovule of a
      flowering plant; an embryonic vesicle. --Goodale.