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

If a banana peel is buried in the soil, microorganisms will work to break it down. — Lauren David, Southern Living, 26 June 2026

Food particles and microorganisms can become trapped in the nicks, grooves, and scratches on the board. — Mary Marlowe Leverette, The Spruce, 28 June 2026

The microbiome is basically the community of tiny microorganisms that live in and on the body, including the gut too. — Lyssanoel Frater, USA Today, 24 June 2026

This vast ecosystem of bacteria and other microorganisms in our intestines shapes our health in profound ways that extend well beyond digestion. — Brittney Melton, NPR, 24 June 2026

Word History

Etymology

International Scientific Vocabulary

First Known Use

1880, in the meaning defined above

Rhymes for microorganism

• activism
• albinism
• altruism
• aneurism
• animism
• aphorism
• atomism
• barbarism
• bolshevism
• botulism
• brahmanism
• calvinism

Kids 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