laser

American Heritage® Dictionary of the English Language, Fourth Edition

1. 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.

Century Dictionary and Cyclopedia

1. n. A gum-resin obtained from the north of Africa, and greatly esteemed by the ancients as an antispasmodic, deobstruent, and diuretic. It is supposed to have been produced by Thapsia Garganica or one of the varieties of that plant. Also called asadulcis.
2. n. An obsolete form of leisure.

Wiktionary

1. n. A gum resin obtained from certain umbelliferous plants.
2. n. Such a plant.
3. n. A device that produces a monochromatic, coherent beam of light.
4. v. To cut with a laser
5. v. sports To throw with laser-like precision

GNU Webster's 1913

1. n. A device which produces an intense, usually narrow, monochromatic beam of coherent light; called also optical maser. It has various forms, and is used in various applications in science and technology. The beam is produced by boosting the majority of the electrons in specific radiation-absorbing atoms in a medium into a higher energy level, from which they are stimulated by their own emitted radiation to drop back synchronously to their lower energy level, and emit light which is in phase (coherent).

WordNet 3.0

1. n. an acronym for light amplification by stimulated emission of radiation; an optical device that produces an intense monochromatic beam of coherent light