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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  

[lay-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

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Etymology

Origin of laser

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

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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

In Tuesday's training session open to the media before City's trip to Leipzig, some players came out looking relaxed in groups but Anderson emerged by himself, doing kick-ups with a laser focus on the ball.

From BBC ● Nov. 6, 2026

Marvell CEO Matt Murphy said that Lumentum’s laser technology and Marvell’s digital signal processors would together create advantages in the marketplace.

From MarketWatch ● Nov. 2, 2026

Tracks like Cybotron’s “Industrial Lies” — “You buy the missile, buy the laser, buy the tank ... Evict the widow, put the money in the bank” — worked as social critique and floor-filler alike.

From Los Angeles Times ● Nov. 2, 2026

In early March, Nvidia announced a multiyear purchase commitment for Lumentum’s advanced laser components.

From The Wall Street Journal ● Nov. 2, 2026

The funny thing was, even with ADHD, when it came to gymnastics, I could be laser focused.

From "Courage to Soar" by Simone Biles

Central Laser Facility in Oxfordshire - home to some of the most powerful lasers on Earth - will also be affected.

From BBC ● Jul. 9, 2026

The research was led by Chunlei Guo, a professor of optics and physics and a senior scientist at the University's Laboratory for Laser Energetics.

From Science Daily ● May 31, 2026

The second, the Laser Retroreflective Array, will help orbiting spacecraft determine precise locations by reflecting laser signals.

From Science Daily ● May 6, 2026

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

From Barron's ● Apr. 30, 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

German companies manufacturing equipment such as industrial lasers in data centres are enjoying strond demand.

From Barron's ● Nov. 3, 2026

He noted that more data-center connectivity needs will also drive demand for lasers, including InP-based ones.

From MarketWatch ● Oct. 26, 2026

Some self-appointed defenders even patrolled the canal at night to make sure no-one was shining torches or lasers at Bukangi.

From BBC ● Oct. 24, 2026

Her team's instrument uses two lasers rather than one, building on theoretical research conducted by Müller and his collaborators.

From Science Daily ● Oct. 22, 2026

Mom’s eyes became like two chocolate-brown lasers, slicing through us from our bedroom doorway.

From "The Season of Styx Malone" by Kekla Magoon

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