noun pen·i·cil·lin \ˌpe-nə-ˈsi-lən\

: a medicine that is used to kill harmful bacteria

Full Definition of PENICILLIN

:  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
:  a salt or ester of a penicillin or a mixture of such salts or esters


New Latin Penicillium
First Known Use: 1929

Other Biochemistry Terms

bile, biodegradable, capsaicin, keratin, metabolism
PENICILLIN Defined for Kids


noun pen·i·cil·lin \ˌpe-nə-ˈsi-lən\

Definition of PENICILLIN for Kids

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


noun pen·i·cil·lin \ˌpen-ə-ˈsil-ən\

Medical Definition of PENICILLIN

:  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)
:  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
:  a salt or ester of a penicillin acid or a mixture of such salts or esters


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