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penicillin
noun
pen·i·cil·lin
ˌpe-nə-ˈsi-lən
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
Medications that may cause an allergic reaction include penicillin, aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs).
—Daniel More, Health, 24 Oct. 2024
Fleming initially struggled to identify the exact strain of the fungus that created the bacteria-free circle in his petri dish, and over the years, several species of Penicillium have been identified as producing penicillin.
—Jack Guy, CNN, 2 Oct. 2024
These reactions are similar to those caused by penicillin and may indicate a serious allergy.5
Sulfonamides
Sulfonamides, commonly known as sulfa drugs, are a group of antibiotics used to treat various bacterial infections.
—Sarah Jividen, Verywell Health, 12 Sep. 2024
Antibiotic resistance Sir Alexander Fleming shared the 1945 Nobel Prize in medicine with Ernst Chain and Sir Edward Florey for the discovery of penicillin and its application in curing bacterial infections.
—Meg Tirrell, CNN, 13 Oct. 2024
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Word History
Etymology
New Latin Penicillium
First Known Use
1929, in the meaning defined at sense 1
Dictionary Entries Near penicillin
Cite this Entry
“Penicillin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/penicillin. Accessed 5 Dec. 2024.
Kids Definition
penicillin
noun
pen·i·cil·lin
ˌpen-ə-ˈsil-ən
: any of several antibiotics or a mixture of these produced by penicillia or in the laboratory and used especially against round disease-producing bacteria
Etymology
from scientific Latin Penicillium "a genus of molds producing antibiotics," from Latin penicillus, literally, "little tail" — related to pencil
Medical Definition
penicillin
noun
pen·i·cil·lin
ˌpen-ə-ˈsil-ən
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
More from Merriam-Webster on penicillin
Nglish: Translation of penicillin for Spanish Speakers
Britannica.com: Encyclopedia article about penicillin
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