penicillin
noun
pen·i·cil·lin
| \ ˌpe-nə-ˈsi-lən
\
\
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
His journey lasted only a few miles (kilometers) when FBI agents boarded the bus and explained that Walton had to return to work at his laboratory at nearby Merck & Co. His mission: to expand supplies of penicillin. — Washington Post, "103-year-old ex-chemist to be honored for work on penicillin," 4 Aug. 2019 But if it's treated with routine antibiotics, including penicillin, the condition could get worse. — Stephanie Innes, azcentral, "Cases of valley fever in Arizona are up in 2019. Here's what you need to know," 10 July 2019 Subsequent to the transplant, the patients developed invasive infections from an E. coli strain that was resistant to a wide variety of antibiotics in the penicillin and cephalosporin groups. — Beth Mole, Ars Technica, "One dead after poop transplant gone wrong, FDA warns," 14 June 2019 A decade after the use of penicillin became widespread, more than half of common Staphylococcus bacteria in big hospitals were resistant to it. — The Economist, "Attack of the superbugs: July 2041," 5 July 2019 Even though penicillin had been proven to treat syphilis by 1947, these men were denied the treatment. — Jason Ashe, The Conversation, "Not all Americans have a fair path to a good death – racial disparities are real," 24 June 2019 In 1928, Alexander Fleming discovered penicillin, the first true antibiotic. — Quanta Magazine, "The Strange Case of Typhoid Mary," 31 Aug. 2016 He was given the last rites by a local priest and was only saved by the first penicillin shipments that reached Italy. — Reagan Alexander, PEOPLE.com, "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, Philly.com, "CHOP study links antibiotic use with risk of kidney stones," 10 May 2018These 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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More Definitions for penicillin
penicillin
noun
English Language Learners Definition of penicillin
: a medicine that is used to kill harmful bacteria
See the full definition for penicillin in the English Language Learners Dictionary
penicillin
noun
pen·i·cil·lin
| \ ˌpe-nə-ˈsi-lən
\
\
Kids Definition of penicillin
: an antibiotic that is produced by a mold and is used against disease-causing bacteria
penicillin
noun
pen·i·cil·lin
| \ ˌpen-ə-ˈsil-ən
\
\
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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