Source : Webster's Revised Unabridged Dictionary (1913)

Antheridium \An`ther*id"i*um\, n.; pl. {Antheridia}. [Anther + ?
   (a Gr. diminutive ending).] (Bot.)
   The male reproductive apparatus in the lower, consisting of a
   cell or other cavity in which spermatozoids are produced; --
   called also {spermary}. -- {An`ther*id"i*al}, a.

Source : WordNet®

antheridium
     n : the male sex organ of spore-producing plants; produces
         antherozoids; equivalent to the anther in flowers
     [also: {antheridia} (pl), {andtheridia} (pl)]