- any organism too small to be viewed by the unaided eye, as bacteria, protozoa, and some fungi and algae.
Origin of microorganism
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for microorganisms
As an adult, Jonah is drawn to study extremophiles, microorganisms that flourish in intense climates.Must-Read Fiction: ‘The Watch,’ ‘Alys, Always,’ ‘The Year of the Gadfly’
Cameron Martin, Lucy Scholes, Amber Dermont
June 19, 2012
“I was fascinated by the role of microorganisms in allowing life on Earth to exist,” she says.The Deadliest Art Ever
May 31, 2010
All such very small plants and animals are known as microorganisms.General Science
Bertha M. Clark
The diseases resulting from the microorganisms are not contagious and do not spread by contact of diseased with healthy animals.
The virulence is not great enough to kill a sufficiently high percentage of rats that eat food containing the microorganisms.
However, very few experiments have been performed to determine the importance, if any, of these microorganisms to the host.
The passage of microorganisms through the digestive tract of Blaberus craniifer mounted under controlled conditions.
- any organism, such as a bacterium, protozoan, or virus, of microscopic size
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
- An organism of microscopic or submicroscopic size, especially a bacterium or protozoan.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- An organism that can be seen only with the aid of a microscope and that typically consists of only a single cell. Microorganisms include bacteria, protozoans, and certain algae and fungi. See Note at germ.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.