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.

Related Words

• bacterium
• microbe
• pathogen
• virus