germ theory

noun

: a theory in medicine: infections, contagious diseases, and various other conditions result from the action of microorganisms

Examples of germ theory in a Sentence

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Two centuries later, Louis Pasteur and Robert Koch helped establish germ theory, which holds that many diseases are caused by infectious agents that multiply in the body. — Jason Liebowitz, New Yorker, 25 Aug. 2026 Lister had studied Louis Pasteur’s germ theory of disease, which posited that infections are caused by bacteria. — Scott Lafee, San Diego Union-Tribune, 11 Aug. 2026 Dubbed the White Wings, the sanitation workers sported white pith helmets and uniforms not unlike the lab coats that doctors began to don in the 1880s as germ theory took hold and antiseptics became associated with health. — Rana Mitter, Harpers Magazine, 4 Aug. 2026 To detain people who looked perfectly healthy, Ragusa’s councillors had to grasp that a disease might incubate unseen—an intuition that arrived roughly five centuries before germ theory could explain it. — Britannica Editors, Encyclopedia Britannica, 21 July 2026 See All Example Sentences for germ theory

Word History

First Known Use

1863, in the meaning defined above

Time Traveler
The first known use of germ theory was in 1863

Rhymes for germ theory

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Browse Nearby Words

germ separator
germ theory
germule
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Cite this Entry

“Germ theory.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/germ%20theory. Accessed 30 Aug. 2026.

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Kids Definition

germ theory

noun
: the theory that infectious and contagious disease results from the action of living things

Medical Definition

germ theory

noun
: a theory in medicine: infections, contagious diseases, and various other conditions (as suppurative lesions) result from the action of microorganisms

More from Merriam-Webster on germ theory

Britannica.com: Encyclopedia article about germ theory

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