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 Even when an effective treatment for syphilis — penicillin — became widely available in the 1940s, the researchers withheld it from the infected men and continued the study for decades, determined to track the disease to its endpoint: autopsy. — Tribune News Service, al, "Stop blaming Tuskegee, critics say. It’s not an ‘excuse’ for current medical racism," 28 Mar. 2021 Even when an effective treatment for syphilis — penicillin — became widely available in the 1940s, the researchers withheld it from the infected men and continued the study for decades, determined to track the disease to its endpoint: autopsy. — April Dembosky Kqed, Los Angeles Times, "It’s not Tuskegee. Current medical racism fuels Black Americans’ vaccine hesitancy," 25 Mar. 2021 Alexander Fleming, who discovered the antibiotic properties of penicillin on an agar plate in 1928, created images using live organisms. — Meenakshi J, Smithsonian Magazine, "How Microbiologists Craft Stunning Art Using Pathogens," 22 Mar. 2021 The Roaring Twenties saw the creation of automobiles, radios, assembly lines, band-aids, concrete mixers, electric razors, penicillin, refrigerators, TVs, and washing machines. — Stephen Mcbride, Forbes, "America Is Transforming Before Our Eyes," 9 Mar. 2021 By then, however, phage therapy had been superseded by penicillin, which had become widely available in the West after the war and quickly established itself as the preferred treatment for bacterial infections. — Nicola Twilley, The New Yorker, "When a Virus Is the Cure," 14 Dec. 2020 Even after penicillin emerged as an effective treatment 15 years later, the researchers withheld the drug and watched as the men died or were ravaged by the effects of untreated syphilis. — Melba Newsome, Scientific American, "We Learned the Wrong Lessons from the Tuskegee ‘Experiment’," 31 Mar. 2021 When penicillin became the top-line treatment for syphilis in 1947, the researchers didn't offer it to the participants. — Kristen Rogers, CNN, "Tuskegee isn't the only reason why some Black people are hesitant to get the coronavirus vaccine," 30 Mar. 2021 The project went on for 40 years, even after penicillin became available. — Trisha Powell Crain | Tcrain@al.com, al, "Alabama school district, once home to infamous Tuskegee study, nears full COVID vaccination level," 23 Mar. 2021

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.

Keep scrolling for more

Learn More about penicillin

Dictionary Entries near penicillin

Statistics for penicillin

Last Updated

29 Apr 2021

Cite this Entry

“Penicillin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/penicillin. Accessed 10 May. 2021.

Style: MLA

MLA

Chicago

APA

Merriam-Webster Check Mark Icon

Keep scrolling for more

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