Source : Webster's Revised Unabridged Dictionary (1913)

Utriculus \U*tric"u*lus\, n. [L., a little womb or matrix, a
   calycle.] (Anat.)
   A little sac, or bag; a utricle; especially, a part of the
   membranous labyrinth of the ear. See the Note under {Ear}.

Source : WordNet®

utriculus
     n : a small pouch into which the semicircular canals open [syn:
         {utricle}]
     [also: {utriculi} (pl)]