2. Zoology a sense organ found in many invertebrate animals, consisting typically of a fluid-filled
sac lined with small sensory hairs and containing one or more tiny, free, sandlike grains, or statoliths: it functions as an organ of balance or equilibrium
Webster’s New World College Dictionary, Fourth Edition, compiled by the
editors of Webster’s New World Dictionaries. Copyright © 2010 by Houghton
Mifflin Harcourt. Published by Houghton Mifflin Harcourt. All rights reserved.