- protozoans of the phylum Ciliophora (or class Ciliata).
- (formerly) any of various microscopic organisms found in infusions of decaying organic matter.
Origin of Infusoria
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for infusoria
To-day we also passed a field of "Red Sea," confervæ or infusoria.Ranching, Sport and Travel
With reference to their origin these organisms were called 'Infusoria.Fragments of science, V. 1-2
These infusoria can only be distinguished by a most powerful microscope.A Voyage round the World
Infusoria and other unicellular animals multiply by division.The Beauties of Nature
Sir John Lubbock
The presence of infusoria in immense numbers is one of the reasons for this.The Book of the Aquarium and Water Cabinet