- a minute or microscopic animal, nearly or quite invisible to the naked eye, as an infusorian or rotifer.
- Archaic. a tiny animal, as a mouse or fly.
noun plural -cules or -cula (-kjʊlə)
- a microscopic animal such as an amoeba or rotifer
“very small animal,” especially a microscopic one, 1590s, from Late Latin animalculum, diminutive of Latin animal (see animal (n.)). Related: Animalcular.