The Collaborative International Dictionary of English v.0.48:

Gonad \Gon"ad\, n.; pl. Gonads. [Gr. ? that which generates.]
   (Anat.)
   One of the masses of generative tissue primitively alike in
   both sexes, but giving rise to either an ovary or a testis; a
   generative gland; a germ gland. --Wiedersheim.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gonad
    n 1: a gland in which gametes (sex cells) are produced [syn:
         gonad, sex gland]