Main Entry: pen·i·cil·lin

Pronunciation: \ˌpe-nə-ˈsi-lən\

Function: noun

Etymology: New Latin Penicillium

Date: 1929

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