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
This region harbors fewer bacteria and other microorganisms than at shallower depths, and there is little local variation in temperature or pressure.
—
Vanessa Bates Ramirez, Scientific American, 11 Aug. 2025
Along with other microorganisms, fungi consume all kinds of organic matter — the remains of dead plants, animals and other living things — and release useful nutrients into the soil to be absorbed by plant roots.
—Beth Botts, Chicago Tribune, 9 Aug. 2025
The scientists were surprised to find that the material was teeming with life-forms, some of which were unknown microorganisms.
—Taylor Nicioli, CNN Money, 1 Aug. 2025
When they are exposed to cold temperatures, the process that allows mold and other fruit-rotting microorganisms to grow is slowed down.
—Jessica Farthing, Southern Living, 21 June 2025
See All Example Sentences for microorganism
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Vanessa Bates Ramirez, Scientific American, 11 Aug. 2025
Along with other microorganisms, fungi consume all kinds of organic matter — the remains of dead plants, animals and other living things — and release useful nutrients into the soil to be absorbed by plant roots.
—Beth Botts, Chicago Tribune, 9 Aug. 2025
The scientists were surprised to find that the material was teeming with life-forms, some of which were unknown microorganisms.
—Taylor Nicioli, CNN Money, 1 Aug. 2025
When they are exposed to cold temperatures, the process that allows mold and other fruit-rotting microorganisms to grow is slowed down.
—Jessica Farthing, Southern Living, 21 June 2025
See All Example Sentences for microorganism
Cite this Entry
“Microorganism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/microorganism. Accessed 20 Aug. 2025.
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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