microorganism

American  

[mahy-kroh-awr-guh-niz-uhm] / ˌmaɪ kroʊˈɔr gəˌnɪz əm /

noun

• microorganisms
  plural

1. any organism too small to be viewed by the unaided eye, as bacteria, protozoa, and some fungi and algae.

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microorganism British  

/ ˌmaɪkrəʊˈɔːɡəˌnɪzəm /

noun

1. any organism, such as a bacterium, protozoan, or virus, of microscopic size

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microorganism Scientific  

/ mī′krō-ôr′gə-nĭz′əm /

1. An organism that can be seen only with the aid of a microscope and that typically consists of only a single cell. Microorganisms include bacteria, protozoans, and certain algae and fungi.

2. See Note at germ

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Other Word Forms

Derived Forms

• microorganic
  adjective
• microorganismal
  adjective

Inflected Forms

Nouns

• microorganisms
  plural

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Etymology

Origin of microorganism

First recorded in 1875–80; micro- + organism

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Explanation

A microorganism is a living thing that is too small to see with the naked eye. Bacteria and amoebas are microorganisms, and while not technically "alive," viruses are also considered microorganisms. The only way to see a microorganism is through a microscope, an instrument used to magnify images of very small things. Microorganisms are fundamental to life on Earth. They decompose dead things, recycle nutrients, aid in digestion, and strengthen our immune systems. They are a key part of biotechnology: Microorganisms are used to treat sewage, clean up pollution, and create medicines. Microorganisms are also used in making foods like bread and cheese. On the negative side, a few microorganisms are harmful, as they can cause disease. Another word for microorganism is microbe.

Example Sentences

See Examples For:

microorganism microorganisms

If these enzymes are attached directly to the outside of a bacterium, they could allow the microorganism to digest the surrounding material while remaining in close contact with it.

From Science Daily ● Oct. 16, 2026

Mr. Gutman is the founder of Primer’s Yeast, a company that sells ancient strains of the microorganism.

From New York Times ● Jun. 20, 2024

"Essentially, one of the tools we developed leverages the structure of this graph in order to determine which pieces of DNA appear repeatedly either across microbes or within the same microorganism."

From Science Daily ● May 7, 2024

The microorganism also been connected to non-fatal, but sight-threatening, eye infections, sometimes through contaminated contact lens solution.

From Seattle Times ● Mar. 13, 2024

"You couldn't expect a microorganism to evolve here that was capable of feeding on Earth-type tissues; they would have starved to death long ago."

From Islands of Space by John Wood Campbell

They wanted to determine not only whether the materials could be completely broken down, but also which microorganisms were responsible and what biological mechanisms allowed them to do it.

From Science Daily ● Oct. 16, 2026

Rather than expecting microorganisms to break down materials that are naturally resistant to decomposition, scientists could develop plastics with chemical structures that make biological recycling possible.

From Science Daily ● Oct. 16, 2026

For microorganisms to make a meaningful difference in reducing plastic pollution, more plastic products would need to be made from biodegradable materials that contain chemical bonds microbes can break apart.

From Science Daily ● Oct. 16, 2026

Instead, the researchers emphasize the importance of designing materials that microorganisms can actually digest.

From Science Daily ● Oct. 16, 2026

Special soil microorganisms are also likely to play a role in its persistent fertility.

From "1491" by Charles C. Mann

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Related Words

• bacterium
• microbe
• pathogen
• virus

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