penicillin

This term refers specifically to a group of antibiotics derived from Penicillium molds. It carries a strong historical connotation of medical breakthrough, often associated with the dawn of the antibiotic era and the transition from fatal bacterial infections to treatable conditions. As a mass noun, it is treated as uncountable when referring to the drug substance in general. To specify a particular amount or type, speakers use partitive constructions such as a dose of penicillin or a course of penicillin.