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
Small but mighty, microorganisms are nature’s chemists.
—
Katherine Bourzac, Quanta Magazine, 15 Sep. 2025
On Earth, such compounds often form when microorganisms consume organic material.
—Gabe Whisnant, MSNBC Newsweek, 10 Sep. 2025
These reactions between substances also demonstrate energy sources that could have been used by early microorganisms.
—Humberto Basilio, Scientific American, 9 Sep. 2025
The results from this third experiment led the researchers to conclude that there likely weren’t microorganisms in the soil.
—Joel S. Levine, The Conversation, 8 Sep. 2025
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Katherine Bourzac, Quanta Magazine, 15 Sep. 2025
On Earth, such compounds often form when microorganisms consume organic material.
—Gabe Whisnant, MSNBC Newsweek, 10 Sep. 2025
These reactions between substances also demonstrate energy sources that could have been used by early microorganisms.
—Humberto Basilio, Scientific American, 9 Sep. 2025
The results from this third experiment led the researchers to conclude that there likely weren’t microorganisms in the soil.
—Joel S. Levine, The Conversation, 8 Sep. 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 18 Sep. 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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