Definition of "animalcule" [an•i•mal•cule]

• A microscopic or minute organism, such as an amoeba or paramecium, usually considered to be an animal. (noun)
• Archaic A tiny animal, such as a mosquito. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "For instance, there is the word animalcule (plural animalcules), also written animalculum (plural animalcula)."
• "Of voluntary capacities and powers the newborn infant possesses little more than the simplest unicellular animalcule, that is, about all it can do is to scent and swallow food."
• "The microscope cannot find the animalcule which is less perfect for being little."