penicillin

noun pen·i·cil·lin \ ˌpe-nə-ˈsi-lən \

|Updated on: 2 Jul 2018

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

See penicillin defined for English-language learners

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Recent Examples of penicillin from the Web

Although penicillin could be manufactured fairly easily in the laboratories at the university, many other drugs were not so simple, even with talent and ingenuity.

— nan randall, The Atlantic, "'Charlottesville': A Government-Commissioned Story About Nuclear War," 25 Jan. 2018
But the strain identified at the Orange County facility is more of a superbug, which produces enzymes that can break down a range of antibiotics in the penicillin family.

— naseem s. miller, OrlandoSentinel.com, "Penicillin-resistant superbug found in Orange County facility, CDC report says," 5 June 2018
Blockbusters including penicillin and statins, which lower cholesterol, came from fungi.

— peter andrey smith, Bloomberg.com, "This Fungus Could Help Cure Cancer," 4 June 2018
Fungi are the basis for many drugs, including the antibiotic penicillin, the immunosuppressant cyclosporine and the cholesterol buster lovastatin, so Blanchette wondered if these Antarctic species might produce any useful molecules.

— peter andrey smith, Scientific American, "Microbes Living in Antarctic Huts Produce Novel Chemical Compounds," 1 June 2018
The tentacles of the program also wound around the infamous Tuskegee syphilis study, in which black men with the disease remained untreated even after the discovery of life-saving penicillin so scientists could track the course of the illness.

— julia m. klein, BostonGlobe.com, "When America imprisoned ‘promiscuous’ women," 23 May 2018
They were not offered treatment throughout the 40 years that the experiment went on, even when, 15 years later, penicillin had become the standard of care.

— megha satyanarayana, STAT, "He was a champion of public health — but played a role in the horrors of Tuskegee. Should a college expunge his name?," 27 Apr. 2018
The drugs ranged from broad-spectrum penicillins, which increased the risk by 27 percent, to sulfa drugs, which were associated with more than double the risk.

— nicholas bakalar, New York Times, "Antibiotics May Raise the Risk for Kidney Stones," 10 May 2018
For a heartier spin on Jewish penicillin, add egg noodles, white rice, or kreplach, dumplings made with ground beef and onion, to the chicken broth for $1.

— samantha nelson, RedEye Chicago, "10 soups to get you through flu season in Chicago," 24 Jan. 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.

Origin and Etymology of penicillin

New Latin Penicillium

NEW! Time Traveler

First Known Use: 1929

in the meaning defined at sense 1

See Words from the same year

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PENICILLIN Defined for English Language Learners

penicillin

noun

Definition of penicillin for English Language Learners

: a medicine that is used to kill harmful bacteria

PENICILLIN Defined for Kids

penicillin

noun pen·i·cil·lin \ ˌpe-nə-ˈsi-lən \

Definition of penicillin for Students

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

Medical Dictionary

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

Learn More about penicillin

Spanish Central: Translation of penicillin Nglish: Translation of penicillin for Spanish speakers Britannica.com: Encyclopedia article about penicillin

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penicillin

Definition of penicillin

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Origin and Etymology of penicillin

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PENICILLIN Defined for English Language Learners

penicillin

Definition of penicillin for English Language Learners

PENICILLIN Defined for Kids

penicillin

Definition of penicillin for Students

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penicillin

medical Definition of penicillin

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