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• laser
  laser

  noun

  a device that produces a nearly parallel, nearly monochromatic, and coherent beam of light by exciting atoms to a higher energy level and causing them to radiate their energy in phase.
• Laser
  Laser

  noun

  a type of dinghy, designed to be sailed by one person

laser

American  

[ley-zer] / ˈleɪ zər /

noun

Physics.

• lasers
  plural

1. a device that produces a nearly parallel, nearly monochromatic, and coherent beam of light by exciting atoms to a higher energy level and causing them to radiate their energy in phase.

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laser ¹ British  

/ ˈleɪzə /

noun

1. a source of high-intensity optical, infrared, or ultraviolet radiation produced as a result of stimulated emission maintained within a solid, liquid, or gaseous medium. The photons involved in the emission process all have the same energy and phase so that the laser beam is monochromatic and coherent, allowing it to be brought to a fine focus

2. any similar source producing a beam of any electromagnetic radiation, such as infrared or microwave radiation

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verb

1. to use a laser on (something), esp as part of medical treatment

2. (often foll by off) to remove (a tattoo, fat, etc) with laser treatment

Laser ² British  

/ ˈleɪzə /

noun

1. a type of dinghy, designed to be sailed by one person

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laser Scientific  

/ lā′zər /

1. Short for light amplification by stimulated emission of radiation. A device that creates and amplifies electromagnetic radiation of a specific frequency through the process of stimulated emission. The radiation emitted by a laser consists of a coherent beam of photons, all in phase and having the same polarization. Lasers have many uses, such as cutting hard or delicate substances, reading data from compact disks and other storage devices, and establishing straight lines in geographical surveying.

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laser Cultural  

1. A device that produces a very narrow, highly concentrated beam of light. Lasers have a variety of uses in such areas as surgery, welding and metal cutting, and sound and video recording and reproduction. The name is an acronym for l ight a mplification by s timulated e mission of r adiation.

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Closer Look

A laser emits a thin, intense beam of nearly monochromatic visible or infrared light that can travel long distances without diffusing. Most light beams consist of many waves traveling in roughly the same direction, but the phases and polarizations of each individual wave (or photon) are randomly distributed. In laser light, the waves are all precisely in step, or in phase, with each other, and have the same polarization. Such light is called coherent. All of the photons that make up a laser beam are in the same quantum state. Lasers produce coherent light through a process called stimulated emission. The laser contains a chamber in which atoms of a medium such as a synthetic ruby rod or a gas are excited, bringing their electrons into higher orbits with higher energy states. When one of these electrons jumps down to a lower energy state (which can happen spontaneously), it gives off its extra energy as a photon with a specific frequency. But this photon, upon encountering another atom with an excited electron, will stimulate that electron to jump down as well, emitting another photon with the same frequency as the first and in phase with it. This effect cascades through the chamber, constantly stimulating other atoms to emit yet more coherent photons. Mirrors at both ends of the chamber cause the light to bounce back and forth in the chamber, sweeping across the entire medium. If a sufficient number of atoms in the medium are maintained by some external energy source in the higher energy state—a condition called population inversion—then emission is continuously stimulated, and a stream of coherent photons develops. One of the mirrors is partially transparent, allowing the laser beam to exit from that end of the chamber. Lasers have many industrial, military, and scientific uses, including welding, target detection, microscopic photography, fiber optics, surgery, and optical instrumentation for surveying.

Other Word Forms

Noun Inflected Forms

• lasers
  plural

Etymology

Origin of laser

1955–60; l(ightwave) a(mplification by) s(timulated) e(mission of ) r(adiation)

Explanation

A laser is a focused beam of light used for many reasons, from eye surgery to gun scopes to laser pointers. The first laser was created more than 50 years ago. The word laser actually stands for "light amplification by stimulated emission of radiation," and the result is a powerful beam of light that happens to be very useful. Many people know lasers from science fiction movies, where aliens fire deadly lasers at Earth. Lasers aren't that dramatic in real life, but they are used in many ways, including surgery and light shows.

Example Sentences

See Examples For:

laser Laser lasers

Rocket Lab said in conjunction with its second-quarter earnings report on Monday that the subsidiary builds on its recent acquisition of laser optical-communications provider Mynaric, which is based in Munich.

From MarketWatch ● Aug. 10, 2026

First attempts to scrub off the paint on the court were not completely successful, so contractors have been on site using "laser technology".

From BBC ● Aug. 8, 2026

That’s the kind of laser focus that can help a young running back such as Omarion Hampton, selected 22nd overall by the Chargers in the 2025 draft.

From Los Angeles Times ● Aug. 5, 2026

LiDAR is an advanced 3D scanning method that sends laser pulses from an aircraft toward the landscape below.

From Science Daily ● Aug. 4, 2026

His focus on Mom is laser sharp, his fingers tugging on longer bits of his hair.

From "South of Somewhere" by Kalena Miller

Venezuelan airlines Estelar, Laser and Plus Ultra also offer flights to the Spanish capital.

From Barron's ● Apr. 30, 2026

Laser eye surgery has been performed on more than 40 million patients worldwide since FDA approval in 1999.

From The Wall Street Journal ● Apr. 24, 2026

Laser Quest told BBC Panorama its "great value for money" and that it's sited in "high cost locations…with significant rent, service charge and business rates"

From BBC ● Mar. 23, 2026

To verify the prototype's performance, researchers used the University of Melbourne's Ultrafast Laser Laboratory within the School of Chemistry.

From Science Daily ● Mar. 22, 2026

I feel a little bad for leaving her, but no way do I want to chase her around Laser Zone all day.

From "Isaiah Dunn Is My Hero" by Kelly J. Baptist

Telecom buyers used to order lasers in the hundreds; Nvidia and the cloud giants want hundreds of millions.

From MarketWatch ● Aug. 7, 2026

The demand for test ranges has dramatically increased in recent years as the military pursued new generation weapons, including drones, lasers and fast-flying hypersonic missiles.

From The Wall Street Journal ● Aug. 7, 2026

The sound combined with lasers and immersive backdrop visuals of scenes from the films elevated the show experience.

From Los Angeles Times ● Aug. 5, 2026

Optical fibers carry information across communication networks, lasers provide highly precise light sources, and optical sensors are widely used in chemistry and biology.

From Science Daily ● Jul. 31, 2026

Zeke was a Hall Monitor again, which suddenly seemed way cooler now that he knew the sashes could shoot lasers.

From "Chronicles of a Lizard Nobody" by Patrick Ness

Related Words

• bar
• glow
• radiation
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