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.
Origin of animalcule
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
noun plural -cules or -cula (-kjʊlə)
a microscopic animal such as an amoeba or rotifer
Word Origin for animalcule
C16: from New Latin animalculum a small animal
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
"very small animal," especially a microscopic one, 1590s, from Late Latin animalculum, diminutive of Latin animal (see animal (n.)). Related: Animalcular.
Online Etymology Dictionary, © 2010 Douglas Harper