actinomyces

noun

ac·​ti·​no·​my·​ces ˌak-(ˌ)ti-nō-ˈmī-ˌsēz How to pronounce actinomyces (audio)
-tə-nō-;
ak-ˌti-nō-
plural actinomyces
: any of a genus (Actinomyces) of filamentous or rod-shaped bacteria that includes usually commensal and sometimes pathogenic forms inhabiting mucosal surfaces especially of the oral cavity of warm-blooded vertebrates

Examples of actinomyces in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Nestled within the dung and dirt was an actinomyces bacteria that issued prominent fungicidal activity against both Candida and Cryptococcus. — Rebecca Kreston, Discover Magazine, 1 Sep. 2015

Word History

Etymology

borrowed from New Latin, genus name, from actino- actino- + -myces -myces

First Known Use

1879, in the meaning defined above

Time Traveler
The first known use of actinomyces was in 1879

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Cite this Entry

“Actinomyces.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/actinomyces. Accessed 26 Sep. 2026.

Medical Definition

1
capitalized : a genus of filamentous or rod-shaped gram-positive bacteria of the family Actinomycetaceae that includes usually commensal and sometimes pathogenic forms inhabiting mucosal surfaces especially of the oral cavity compare actinomycosis
2
plural actinomyces : a bacterium of the genus Actinomyces
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