Source : Webster's Revised Unabridged Dictionary (1913)

Ventriculus \Ven*tric"u*lus\, n.; pl. {Ventriculi}. [L., belly,
   dim. fr. venter belly.] (Zo["o]l.)
   (a) One of the stomachs of certain insects.
   (b) The body cavity of a sponge.

Source : WordNet®

ventriculus
     n : thick-walled muscular pouch below the crop in many birds and
         reptiles for grinding food [syn: {gizzard}, {gastric mill}]
     [also: {ventriculi} (pl)]