n.
Any of several devices that emit highly amplified and coherent radiation of one or more discrete frequencies. One of the most common lasers makes use of atoms in a metastable energy state that, as they decay to a lower energy level, stimulate others to decay, resulting in a cascade of emitted radiation.
[l(ight) a(mplification by) s(timulated) e(mission of) r(adiation).]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
