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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

Still, the Roadster’s debut had the air of an outdoor concert, complete with fog and red laser lights as content creators flanked a main stage.

From The Wall Street Journal ● Oct. 16, 2026

Her director, who seems preoccupied with grass and trees and skies at the expense of people, has made a film almost completely bereft of wit, which is like a Star Wars movie without laser guns.

From The Wall Street Journal ● Oct. 15, 2026

Powerful laser microscopy revealed the mechanism: after a day or two of contact, the corals' tissues began fusing, creating a "nutrient highway" between the pair.

From Barron's ● Oct. 14, 2026

Outside of work, Kariem enjoyed creating products with his laser engraver and 3D printers, as well as cooking, watching anime and spending time with family and friends, according to his profile on the school's website.

From BBC ● Oct. 14, 2026

That afternoon on the bus, Howard ignored my laser thoughts again and made a beeline right for me.

From "Wish" by Barbara O'Connor

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 race to build AI infrastructure has created urgent demand for providers who can deliver at speed without sacrificing reliability,” says Ross Laser, Magnetar’s president and co-founder.

From The Wall Street Journal ● Jun. 10, 2026

Laser reception requires fewer relays and can be located at the data center, rather than relayed from a special antenna.

From The Wall Street Journal ● May 12, 2026

Venezuela's Laser Airlines will operate the same route from May 1.

From Barron's ● Apr. 30, 2026

“Wait till your relatives see you riding around in a Laser XL7,” remarked Matt.

From "Ralph S. Mouse" by Beverly Cleary

For more serious scarring, dermatologists can recommend more aggressive treatments such as lasers that probe deeper into the skin.

From Los Angeles Times ● Oct. 13, 2026

By using more powerful lasers and developing higher-quality thorium crystals, they hope to substantially increase its precision.

From Science Daily ● Oct. 11, 2026

Sixth-generation aircraft will likely include more advanced stealth features than their fifth-generation predecessors, sensors that use artificial intelligence and be armed with lasers or hypersonic weapons, according to the Congressional Research Service.

From The Wall Street Journal ● Sep. 30, 2026

The indium phosphide-based lasers are used inside optical transceivers, which connect networking equipment and transmit data across data centers.

From MarketWatch ● Sep. 19, 2026

Or play really intense music that sounds like lasers?

From "Dumplin'" by Julie Murphy

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