actinomycin

noun

ac·ti·no·my·cin ˌak-(ˌ)ti-nō-ˈmī-sᵊn

-tə-nō-;

ak-ˌti-nō-

: any of various red or yellow-red mostly toxic polypeptide antibiotics isolated from soil bacteria (especially Streptomyces antibioticus)

specifically : one used to inhibit DNA or RNA synthesis

Etymology

New Latin Actinomyces actinomyces + -in entry 1

First Known Use

1940, in the meaning defined above

Time Traveler

The first known use of actinomycin was in 1940

See more words from the same year

actinomycete

actinomycin

actinomycosis

See all Nearby Words

Style

“Actinomycin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/actinomycin. Accessed 6 Feb. 2026.

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actinomycin

noun

ac·ti·no·my·cin -ˈmīs-ᵊn

: any of various red or yellow-red mostly toxic polypeptide antibiotics isolated from soil bacteria (especially Streptomyces antibioticus)

specifically : one used to inhibit DNA or RNA synthesis