contractile vacuole

noun Cell Biology.

a membrane-enveloped cellular organelle, found in many microorganisms, that periodically expands, filling with water, and then contracts, expelling its contents to the cell exterior: thought to be important in maintaining hydrostatic equilibrium.

Origin of contractile vacuole

First recorded in 1875–80

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018