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

A growing number of studies have demonstrated the positive effects on the human immune system, moods and the microbiome, as the microorganism population of the body is known.

From Science Daily ● Nov. 15, 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

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

The main threat is a root rot in the trees caused by a soil-borne pathogen called Phytophthora, a new strain of the same microorganism that helped cause the Irish famine of the 1840s.

From Salon ● Dec. 18, 2023

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.

Preliminary findings suggest that the therapies may reduce bacterial species associated with periodontal disease while increasing microorganisms linked to healthier gums.

From Science Daily ● Aug. 30, 2026

UV radiation is deadly enough to many microorganisms that hospitals routinely use it for sterilization.

From Science Daily ● Aug. 25, 2026

Even so, the discovery offers a new way to think about the relationships between microorganisms and animals.

From Science Daily ● Aug. 17, 2026

PHAs are especially notable because of their biological circularity: They are made by microorganisms and can also be broken down through biological processes.

From Science Daily ● Aug. 17, 2026

On the other hand, it was argued that, on so windy a planet as Mars, microorganisms should be everywhere if they are anywhere.

From "Cosmos" by Carl Sagan

Related Words

• bacterium
• microbe
• pathogen
• virus