SINCE 1828
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
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 Along with flu shots, others that tend to cause stinging and soreness later are tetanus, MMR (measles, mumps and rubella), pneumonia, typhoid, and some antibiotics, like penicillin, Stewart explained. — Erica Sweeney, Teen Vogue, "Why Do Some Vaccines Hurt More Than Others?," 24 Oct. 2018 People with certain neurological or cardiac forms of illness may require intravenous treatment with antibiotics such as ceftriaxone or penicillin. — Kara Driscoll, ajc, "Lyme disease: 7 questions answered about tick-borne infections," 7 May 2018 That's one of the reasons scarlet fever was a leading cause of heart disease for adults before penicillin was discovered. — Meera Senthilingam And Sandee Lamotte, CNN, "Health agency warns UK parents as scarlet fever cases soar," 27 Mar. 2018 At the time, Harris likened the proliferation of medical pot to telling patients to chew on mold instead of taking penicillin. — Jenna Portnoy, Washington Post, "D.C.’s biggest pot proselytizer moves to Maryland to take on his nemesis, Rep. Andy Harris," 10 Apr. 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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