from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The many minute aquatic creatures, such as protozoa and unicellular algae found in fresh water habitats

from the GNU version of the Collaborative International Dictionary of English

  • One of the classes of Protozoa, including a large number of species, all of minute size. Formerly, the term was applied to any microbe found in infusions of decaying organic material, but the term is now applied more specifically to one of the classes of the phylum Ciliophora, of ciliated protozoans.

from The Century Dictionary and Cyclopedia

  • A name given by Otho Fr. Müller to an indiscriminate assemblage of minute, and for the most part microscopic, animal and vegetable organisms frequently developed in infusions of decaying organic substances.
  • A class of minute, mostly microscopic, animalcules, provisionally regarded as the highest class of Protozoa.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. in some recent classifications, coextensive with the Ciliata: minute organisms found in decomposing infusions of organic matter


Sorry, no etymologies found.


  • The microscope revealed the complexity of organic tissues, the existence of minute creatures, vaguely called infusoria, and the strange inhabitants of the blood, the red and white corpuscles.

    The Mind in the Making The Relation of Intelligence to Social Reform

  • There are certain minute animal productions called infusoria and organisms peculiar to each portion of the globe.

    A Voyage round the World A book for boys

  • In 1838, Christian Gottfried Ehrenberg gave a description of the finer structure of the "infusoria" but it was Ferdinad Cohn, who in 1854 first ascertained with certainty that bacteria belonged to the vegetable kingdom.

    The Catholic Encyclopedia, Volume 10: Mass Music-Newman

  • It is possible that the infusoria under the microscope do the same.

    The War of The Worlds

  • Were it only by the identity of the law, the evolution of the comet in the firmament to the whirling of the infusoria in the drop of water.

    Les Miserables

  • It proves the presence of decomposing organic matter in the water — it is full of infusoria.

    An Enemy of the People

  • Furthermore, it has been found that experiments made in the manner described above answer well with most infusions; but that if you fill the vessel with boiled milk, and then stop the neck with cotton-wool, you ‘will’ have infusoria.


  • These experiments, you see, all tended towards one conclusion — that the infusoria were developed from little minute spores or eggs which were constantly floating in the atmosphere, which lose their power of germination if subjected to heat.


  • The reports were endorsed by P.L. Smith, W. Kleinschmidt, Charles Kovar, Louis Forgeron and D. Herrero, which covered all the worlds 'authorities in the disciplines of fish parasites, ringworm, botany, infusoria and aphids.

    The War with the Newts

  • It is like a drop of water seen through a microscope, a single drop teeming with infusoria; or a speck of cheese full of mites invisible to the naked eye.

    Studies in Pessimism


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  • Makes me think of unknown detritus floating in tea.

    March 5, 2019

  • Oh sing out Hosannah! and Gloria!;

    Surrender to springtime euphoria!

    The world is new rife

    With infinite life -

    Great mammals to least infusoria!

    March 2, 2019

  • When this term is a taxonomic category (the vast majority of cases cited here), its first letter is capitalized (Infusoria).

    July 6, 2013

  • "It is possible that the infusoria under the microscope do the same."

    - H.G. Wells, The War of the Worlds

    December 23, 2008