Source : Webster's Revised Unabridged Dictionary (1913)

Ovum \O"vum\, n.; pl. L. {Ova}, E. {Ovums}. [L., an egg. See
   {Oval}.]
   1. (Biol.) A more or less spherical and transparent mass of
      granular protoplasm, which by a process of multiplication
      and growth develops into a mass of cells, constituting a
      new individual like the parent; an egg, spore, germ, or
      germ cell. See Illust. of {Mycropyle}.

   Note: The ovum is a typical cell, with a cell wall, cell
         substance, nucleus, and nucleolus. In man and the
         higher animals the cell wall, a vertically striated
         membrane, is called the zona pellucida; the cell
         contents, the vitellus; the nucleus, the germinal
         vesicle; and the nucleolus, the germinal spot. The
         diameter of the ripe ovum in man and the domestic
         animals varies between 1-200 and 1-120 of an inch.

   2. (Arch.) One of the series of egg-shaped ornaments into
      which the ovolo is often carved. --Gwilt.

Source : WordNet®

ovum
     n : the female reproductive cell; the female gamete [syn: {egg
         cell}]
     [also: {ova} (pl)]