[ in-fyoo-sawr-ee-uh, -sohr- ]
/ ˌɪn fyʊˈsɔr i ə, -ˈsoʊr- /

plural noun

protozoans of the phylum Ciliophora (or class Ciliata).
(formerly) any of various microscopic organisms found in infusions of decaying organic matter.

Origin of Infusoria

1780–90; < New Latin, neuter plural of infūsōrius. See infuse, -ory1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for infusoria