/ Dictionary / Index I Infusoria: Meaning and Definition of Find definitions for: In•fu•so•ri•a Pronunciation: (in"fyoo-sôr'ē-u, -sōr'-), [key] — n.pl. protozoans of the phylum Ciliophora (or class Ciliata). (formerly) any of various microscopic organisms found in infusions of decaying organic matter. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: infusoria (Thesaurus) infusive infusorial Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language