Paramecium Par·a·me·ci·um (pār'ə-mē'shē-əm, -sē-əm)
A genus of freshwater ciliate protozoans, characteristically slipper-shaped and covered with cilia, and commonly used for genetic research and other studies.
Plural paramecia or parameciums
Any of various freshwater protozoans of the genus Paramecium that are usually oval in shape and that move by means of cilia. Although they consist of a single cell, paramecia are large enough to be visible to the naked eye. Like other ciliates, paramecia contain two nuclei, a macronucleus and a micronucleus. On the cellular surface is a groove that opens into a gullet, into which food particles are absorbed.