One entry found for penicillin.

Main Entry: pen·i·cil·lin
Pronunciation: pen--sil-n
Function: noun
Etymology: from scientific Latin Penicillium "a genus of molds producing antibiotics," from Latin penicillus, literally, "little tail" --related to PENCIL
: any of several antibiotics or a mixture of these produced by penicillia or in the laboratory and used especially against round disease-producing bacteria