n. [ As if fr. a L. animalculum, dim. of animal. ] 1. A small animal, as a fly, spider, etc. [ Obs. ] Ray. [ 1913 Webster ]

2. (Zool.) An animal, invisible, or nearly so, to the naked eye. See Infusoria. [ 1913 Webster ]

☞ 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 Desmidiacæ, and the siliceous Diatomaceæ. [ 1913 Webster ]

Spermatic animalcules. See Spermatozoa. [ 1913 Webster ]