tet·​ra·​cy·​cline ˌte-trə-ˈsī-ˌklēn How to pronounce tetracycline (audio)
: a yellow crystalline broad-spectrum antibiotic C22H24N2O8 produced by streptomyces or synthetically
also : any of several chemically related antibiotics (such as doxycycline)

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Most chemical names are made up of two or more Greek and Latin roots strung together. Thus, tetracycline, with its cycl- root from the Greek word for "circle", means "four-ringed"—that is, "consisting of four fused hydrocarbon rings". Antibiotics work against bacteria and other tiny organisms (but not viruses); tetracycline, which comes from a kind of soil bacteria, is one of the most used of the antibiotics. "Broad-spectrum" antibiotics work well on numerous organisms; thus, tetracycline has proved effective against acne, chlamydia, cholera, rickets, and various lung and eye infections, among many other conditions.

Example Sentences

Recent Examples on the Web In response to tetracyclines' susceptibility to efflux pumps, for example, researchers modified tetracycline to make tigecycline, which is not pumped out of the bacteria so easily. Bill Sullivan, Discover Magazine, 3 Nov. 2021 In particular, the sale and distribution of tetracycline, which accounted for 65% of the medically important antibiotics, fell by only 1%, according to the latest annual report from the Food and Drug Administration. Ed Silverman, STAT, 12 Dec. 2022 There is at least one drug, tetracycline, that over time can break down into a substance that can damage the kidney. Dr. Keith Roach, oregonlive, 8 July 2022 This strain has a high-level of resistance to azithromycin and resistance to ceftriaxone, cefixime, cefotaxime, ciprofloxacin and tetracycline. Bruce Y. Lee, Forbes, 21 June 2022 Oxitec uses the antibiotic tetracycline to raise its bugs and mass produce them. Melody Petersenstaff Writer, Los Angeles Times, 8 Apr. 2022 Like steroids do for humans, antibiotics such as tetracycline can bulk some animals up more quickly. Washington Post, 7 Apr. 2022 Laboratory testing found that 20 of these cases were resistant to common antibiotics such as chloramphenicol, streptomycin, sulfamethoxazole and tetracycline. Sandee Lamotte, CNN, 25 Aug. 2021 Using genetic-engineering techniques, the company altered the male mosquitoes to pass down a gene that makes females need a dash of the antibiotic tetracycline to survive. Robert Lee Hotz, WSJ, 31 May 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'tetracycline.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


International Scientific Vocabulary tetracyclic having four fused hydrocarbon rings + -ine entry 2

First Known Use

1952, in the meaning defined above

Time Traveler
The first known use of tetracycline was in 1952

Dictionary Entries Near tetracycline

Cite this Entry

“Tetracycline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/tetracycline. Accessed 5 Feb. 2023.

Kids Definition


tet·​ra·​cy·​cline ˌte-trə-ˈsī-ˌklēn How to pronounce tetracycline (audio)
: a yellow crystalline antibiotic produced by a soil bacterium or made synthetically

Medical Definition


tet·​ra·​cy·​cline ˌte-trə-ˈsī-ˌklēn How to pronounce tetracycline (audio) -klən How to pronounce tetracycline (audio)
: a yellow crystalline broad-spectrum antibiotic that is produced by a soil actinomycete of the genus Streptomyces (S. viridifaciens) or made synthetically and that is administered chiefly in the form of its hydrochloride C22H24N2O8·HCl
also : any of several chemically related antibiotics (as doxycycline)

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