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
Healthy soil depends on beneficial microorganisms to break down nutrients and support plant roots.
—
Jessica Safavimehr, Southern Living, 11 May 2026
Fed with hydrogen, the microorganism biologically converts carbon dioxide in the biogas into additional methane, increasing the fuel quality of the final gas stream.
—New Atlas, 9 May 2026
Scientists estimate there may be between 700,000 and 1 million species in the ocean (mostly animals and excluding most microorganisms, of which there are millions).
—Kurt Snibbe, Oc Register, 8 May 2026
An altered Antarctic landscape could have significant impacts on its wildlife, from the microorganisms and algae that prop up the food chain – food for krill which, in turn, feed many of the region’s whales – to the penguins and seals that rely on sea ice for feeding and resting.
—Laura Paddison, CNN Money, 8 May 2026
See All Example Sentences for microorganism
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Jessica Safavimehr, Southern Living, 11 May 2026
Fed with hydrogen, the microorganism biologically converts carbon dioxide in the biogas into additional methane, increasing the fuel quality of the final gas stream.
—New Atlas, 9 May 2026
Scientists estimate there may be between 700,000 and 1 million species in the ocean (mostly animals and excluding most microorganisms, of which there are millions).
—Kurt Snibbe, Oc Register, 8 May 2026
An altered Antarctic landscape could have significant impacts on its wildlife, from the microorganisms and algae that prop up the food chain – food for krill which, in turn, feed many of the region’s whales – to the penguins and seals that rely on sea ice for feeding and resting.
—Laura Paddison, CNN Money, 8 May 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 12 May. 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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