laser(n = noun.artifact) optical maser - an acronym for light amplification by stimulated emission of radiation; an optical device that produces an intense monochromatic beam of coherent light;
is a kind of optical device
is a part of photocoagulator

   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 1.5]

laser, n. a device that generates an intense beam of coherent monochromatic radiation in the infrared, visible, or ultraviolet region of the electromagnetic spectrum, by stimulated emission of photons from an excited source.

Etymology:
light amplification by stimulated emission of radiation: cf. MASER

N  luminary, light, flame, spark, scintilla, phosphorescence, fluorescence, sun, orb of day, Phoebus, Apollo, Aurora, star, orb, meteor, falling star, shooting star, blazing star, dog star, Sirius, canicula, Aldebaran, constellation, galaxy, zodiacal light, anthelion, day star, morning star, Lucifer, mock sun, parhelion, phosphor, phosphorus, sun dog, Venus, aurora, polar lights, northern lights, aurora borealis, southern lights, aurora australis, lightning, chain lightning, fork lightning, sheet lightning, summer lightning, ball lightning, kugelblitz, phosphorus, yellow phosphorus, scintillator, phosphor, firefly luminescence, ignis fatuus, Jack o'lantern, Friar's lantern, will-o'-the- wisp, firedrake, Fata Morgana, Saint Elmo's fire, glowworm, firefly, June bug, lightning bug, anglerfish, gas, gas light, lime light, lantern, lanthorn, dark lantern, bull's-eye, candle, bougie, taper, rushlight, oil, wick, burner, Argand, moderator, duplex, torch, flambeau, link, brand, gaselier, chandelier, electrolier, candelabrum, candelabra, girandole, sconce, luster, candlestick, lamp, light, incandescent lamp, tungsten bulb, light bulb, flashlight, torch, arc light, laser, maser neon bulb, neon sign, fluorescent lamp, filament, socket, contacts, filler gas, firework, fizgig, pyrotechnics, rocket, lighthouse, self-luminous, glowing, phosphoric, phosphorescent, fluorescent, incandescent, luminescent, chemiluminescent, radiant, blossomed the lovely stars, the forget-me-nots of the angels, the sentinel stars set their watch in the sky, the planets in their station list'ning stood, the Scriptures of the skies, that orbed continent, the fire that severs day from night.

laser beam, laser disk, laser light, laser printer, laser surgery