or  b-lactam  n :  any of a large class of natural and semisynthetic antibiotics (as the penicillins and cephalosporins) with a lactam ring .
 b-lactamase var of  BETA-LACTAM, BETA-LACTAMASE.
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.