saccule
n 1: a small sac or pouch (especially the smaller chamber of the
membranous labyrinth) [syn: {saccule}, {sacculus}]
Saccule \Sac"cule\, n. [L. sacculus, dim. of saccus sack.]
A little sac; specifically, the sacculus of the ear.
[1913 Webster]