The Collaborative International Dictionary
beta-lactam antibiotic
Lactam \Lac"tam\, n. [Lactone + amido.] (Chem.) One of a series of anhydrides of an amido type, analogous to the lactones, as oxindol; a cyclic amide. beta-lactam or [beta]-lactam,
a lactam in which the amide bond is contained within a four-membered ring, which includes the amide nitrogen and the carbonyl carbon.
an antibiotic containing a beta-lactam, such as a penicillin, cephalosporin, or carbapenem; also called a beta-lactam antibiotic. [informal, laboratory slang]