Noun. 1. lysozyme-an enzyme found in saliva and sweat and tears that destroys the cell walls of certain bacteria. muramidase. enzyme-any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions.1  Facebook.y·so·zyme. n. An enzyme occurring naturally in egg white, human tears, saliva, and other body fluids, capable of destroying the cell walls of certain bacteria and thereby acting as a mild antiseptic.