Laser - definition of laser by The Free Dictionary
laser la·ser (lā′zər) n. 1. a. Any of several devices that emit highly amplified and coherent radiation of one or more discrete wavelengths. One of the most common lasers makes use of atoms in a metastable energy state, which, as they decay to a lower energy level, stimulate others to decay, resulting in a cascade of emitted radiation. b. A beam of ...