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
Some of that carbon ends up in leaves, stems, and flowers, and some is sent belowground to build roots and feed soil microorganisms.
—
Dr. Avishesh Neupane, Hartford Courant, 21 Mar. 2026
The movie explores a few unique forms that extraterrestrial life could take, from space microorganisms that produce both infrared light and an unfathomable amount of energy, to rocklike aliens that live under crushing pressure and breathe ammonia.
—Mary Magnuson, The Conversation, 20 Mar. 2026
Compost also fuels beneficial soil microorganisms, a growing front in the fight for healthier soil, according to Allison, who says agribusiness companies might soon be able to mass-produce soil-enriching microbes that farmers can spread on fields.
—Matt Alderton, USA Today, 18 Mar. 2026
In your intestines, colonies of microorganisms (bacteria, fungi, viruses, and others) make up the gut microbiome.
—Mark Gurarie, Verywell Health, 12 Mar. 2026
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Dr. Avishesh Neupane, Hartford Courant, 21 Mar. 2026
The movie explores a few unique forms that extraterrestrial life could take, from space microorganisms that produce both infrared light and an unfathomable amount of energy, to rocklike aliens that live under crushing pressure and breathe ammonia.
—Mary Magnuson, The Conversation, 20 Mar. 2026
Compost also fuels beneficial soil microorganisms, a growing front in the fight for healthier soil, according to Allison, who says agribusiness companies might soon be able to mass-produce soil-enriching microbes that farmers can spread on fields.
—Matt Alderton, USA Today, 18 Mar. 2026
In your intestines, colonies of microorganisms (bacteria, fungi, viruses, and others) make up the gut microbiome.
—Mark Gurarie, Verywell Health, 12 Mar. 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 31 Mar. 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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