penicillin

pen·i·cil·lin   (pěn'ĭ-sĭl'ĭn)    n.  Any of a group of broad-spectrum antibiotic drugs obtained from penicillium molds or produced synthetically, most active against gram-positive bacteria and used in the treatment of various infections and diseases. [penicill(ium) + -in.]

penicillin

An antibiotic that is used to treat infections caused by some kinds of bacteria. Penicillin, which is derived from a common kind of mold that grows on bread and fruit, was the first antibiotic discovered and put into widespread use.

Note: Penicillin was first widely used during World War II.

penicillin 

Main Entry: pen·i·cil·lin
Pronunciation: "pen-&-'sil-&n
Function: noun
1 : a mixture of relatively nontoxic antibioticacids produced especially by molds of the genus Penicillium (as P. notatum or P. chrysogenum) and having a powerful bacteriostatic effect against various bacteria (asstaphylococci, 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 penicillinmixture 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 amixture of such salts or esters

penicillin pen·i·cil·lin (pěn'ĭ-sĭl'ĭn)
n.
Any of a group of broad-spectrum antibiotic drugs obtained from penicillium molds or produced synthetically, most active against gram-positive bacteria and used in the treatment of various infections and diseases.

penicillin   (pěn'ĭ-sĭl'ĭn)  Pronunciation Key  An antibiotic drug obtained from molds of the genus Penicillium and used to treat or prevent various infections caused by gram-positive bacteria such as streptococcus. Penicillin was the first of a class of antibiotics (whose names end in -icillin) that are derived from it and are active against a broader spectrum of bacteria. See Note at Alexander Fleming.