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

Etymology

Origin of microorganism

First recorded in 1875–80; micro- + organism

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

“The presence of terrestrial microorganism within a sample of Ryugu underlines that microorganisms are the world's greatest colonizers and adept at circumventing contamination controls,” the authors conclude.

From Salon ● Nov. 24, 2024

Unlike bacteria, the microorganism is less likely to exchange genetic material with other microbes and doesn't take up residence in the gastrointestinal tract where it could potentially disrupt microbial communities.

From Science Daily ● Nov. 20, 2024

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

This microorganism is transmitted to the healthy birds by the feed, or water becoming contaminated with the discharges from the diseased birds.

From Common Diseases of Farm Animals by R. A. Craig, D.V.M.

This combination suggests that the microorganisms are not simply biological remains from the distant past.

From Science Daily ● Aug. 7, 2026

They also discovered that marine microorganisms behave like selective eaters, favoring fresh carbon from the ocean over older carbon released from permafrost.

From Science Daily ● Aug. 3, 2026

There, microorganisms can break it down and release greenhouse gases that contribute to climate change.

From Science Daily ● Aug. 3, 2026

These measurements reveal how much CO2 microorganisms have released after consuming organic material.

From Science Daily ● Aug. 3, 2026

Might Martian microorganisms returned to Earth pose a public health hazard?

From "Cosmos" by Carl Sagan

Related Words

• bacterium
• microbe
• pathogen
• virus