microorganism
noun
mi·cro·or·gan·ism
ˌmī-krō-ˈȯr-gə-ˌni-zəm 
: an organism (such as a bacterium or protozoan) of microscopic or ultramicroscopic size
Examples of microorganism in a Sentence
Recent Examples on the Web
An ancient microorganism that figured out how to keep its cellular structures intact through 40,000 years of deep freeze could someday inspire a product that keeps a soldier’s skin from freezing on an Arctic patrol.
—
Ryan Brennan, Miami Herald, 13 Feb. 2026
Whale falls, which occur when a whale carcass sinks to the ocean floor, create temporary ecosystems that feed octopuses, sharks, crabs, microorganisms and more.
—Ryan Brennan, Kansas City Star, 13 Feb. 2026
Refrigeration helps slow the growth of harmful microorganisms, preserving the flavor and safety of the jam.
—Katie Rosenhouse, Southern Living, 12 Feb. 2026
Favoring plant protein comes with a bonus, says Ben-Asher, because the dietary fiber and phytonutrients only found in plants is fuel for healthy microorganisms that colonize gut microbiota.
—Rachel Reiff Ellis, SELF, 5 Feb. 2026
See All Example Sentences for microorganism
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Ryan Brennan, Miami Herald, 13 Feb. 2026
Whale falls, which occur when a whale carcass sinks to the ocean floor, create temporary ecosystems that feed octopuses, sharks, crabs, microorganisms and more.
—Ryan Brennan, Kansas City Star, 13 Feb. 2026
Refrigeration helps slow the growth of harmful microorganisms, preserving the flavor and safety of the jam.
—Katie Rosenhouse, Southern Living, 12 Feb. 2026
Favoring plant protein comes with a bonus, says Ben-Asher, because the dietary fiber and phytonutrients only found in plants is fuel for healthy microorganisms that colonize gut microbiota.
—Rachel Reiff Ellis, SELF, 5 Feb. 2026
See All Example Sentences for microorganism
Cite this Entry
“Microorganism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microorganism. Accessed 18 Feb. 2026.
Copy CitationKids Definition
microorganism
noun
mi·cro·or·gan·ism
ˌmī-krō-ˈȯr-gə-ˌniz-əm
: an organism (as a bacterium) of microscopic or less than microscopic size
Medical Definition
microorganism
noun
mi·cro·or·gan·ism
-ˈȯr-gə-ˌniz-əm
: an organism of microscopic or ultramicroscopic size
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