Webster's Revised Unabridged Dictionary · 1913

Animalcule

Animalcule ({not transcribed}) , noun

[As if from a Latin animalculum, dim. of animal.]

1.
A small animal, as a fly, spider, etc. [Obsolete] — Ray
2.
(Zoology) An animal, invisible, or nearly so, to the naked eye. See Infusoria.

Many of the so-called animalcules have been shown to be plants, having locomotive powers something like those of animals. Among these are Volvox, the Desmidiaca, and the siliceous Diatomacea.

Collocations (1)
Spermatic animalcules , See Spermatozoa.