pen·​i·​cil·​lin | \ ˌpe-nə-ˈsi-lən How to pronounce penicillin (audio) \

Definition of penicillin

1 : any of several relatively nontoxic antibiotic acids of the general formula C9H11N2O4SR that are produced by molds (genus Penicillium and especially P. notatum or P. chrysogenum) or synthetically and are used especially against gram-positive cocci also : a mixture of such acids
2 : a salt or ester of a penicillin or a mixture of such salts or esters

Examples of penicillin in a Sentence

Recent Examples on the Web

He was given the last rites by a local priest and was only saved by the first penicillin shipments that reached Italy. Reagan Alexander,, "Five Things You Never Knew About Luciano Pavarotti, the Larger Than Life Opera Star," 13 June 2019 Regular penicillin did not appear to have an impact on kidney stones. Tom Avril,, "CHOP study links antibiotic use with risk of kidney stones," 10 May 2018 Aidy Bryant gave her a special gift for the occasion: her penicillin allergy bracelet. Christian Allaire, Vogue, "On SNL, BTS Performs, Lori Loughlin Is In Jail, and More of the Best Skits," 14 Apr. 2019 Innovations such as penicillin and the measles vaccine have saved hundreds of millions of lives. Bill Gates, WSJ, "Bill Gates: The Best Investment I’ve Ever Made," 16 Jan. 2019 Other studies have shown high concentrations of penicillin and other drugs in runoff from farms and near pharmaceutical plants. Jonathon Keats, Discover Magazine, "Bacteria That Eat Drugs Could Help Solve the Antibiotic Resistance Crisis," 8 Nov. 2018 Turns out some drugs can allow blood to seep into your urine, including penicillin, nonsteroidal anti-inflammatory pain relievers, and the anti-cancer medicine cyclophosphamide, the Mayo Clinic says. Korin Miller, SELF, "10 Things That Can Cause Blood in Your Urine," 19 Sep. 2018 The category Dantas chose to analyze includes the granddaddy of all antibiotic drugs: penicillin. Jonathon Keats, Discover Magazine, "Bacteria That Eat Drugs Could Help Solve the Antibiotic Resistance Crisis," 8 Nov. 2018 Individuals in the study were not told they were infected with the disease or treated with penicillin. Amy Dockser Marcus, WSJ, "For Some African-Americans, Genetic Testing Reopens Past Wounds," 14 July 2018

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

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First Known Use of penicillin

1929, in the meaning defined at sense 1

History and Etymology for penicillin

New Latin Penicillium

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Statistics for penicillin

Last Updated

18 Jun 2019

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Time Traveler for penicillin

The first known use of penicillin was in 1929

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English Language Learners Definition of penicillin

: a medicine that is used to kill harmful bacteria


pen·​i·​cil·​lin | \ ˌpe-nə-ˈsi-lən How to pronounce penicillin (audio) \

Kids Definition of penicillin

: an antibiotic that is produced by a mold and is used against disease-causing bacteria


pen·​i·​cil·​lin | \ ˌpen-ə-ˈsil-ən How to pronounce penicillin (audio) \

Medical Definition of penicillin

1 : a mixture of relatively nontoxic antibiotic acids produced especially by molds of the genus Penicillium (as P. notatum or P. chrysogenum) and having a powerful bacteriostatic effect against various chiefly gram-positive bacteria (as staphylococci, gonococci, pneumococci, hemolytic streptococci, or some meningococci)
2 : any of numerous often hygroscopic and unstable amido acids (as penicillin G, penicillin O, and penicillin V) that have a structure in which a four-membered lactam ring shares a nitrogen and a carbon atom with a thiazolidine ring to which it is fused and that are components of the penicillin mixture or are produced biosynthetically by the use of different strains of molds or different media or are synthesized chemically
3 : a salt or ester of a penicillin acid or a mixture of such salts or esters

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More from Merriam-Webster on penicillin

Spanish Central: Translation of penicillin

Nglish: Translation of penicillin for Spanish Speakers Encyclopedia article about penicillin

Comments on penicillin

What made you want to look up penicillin? Please tell us where you read or heard it (including the quote, if possible).


incapable of being surmounted or overcome

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