photon

[ foh-ton ]

/ ˈfoʊ tɒn /

noun

a quantum of electromagnetic radiation, usually considered as an elementary particle that is its own antiparticle and that has zero rest mass and charge and a spin of one. Symbol: γ

Nearby words

photomorphogenesis, photomosaic, photomultiplier, photomural, photomyoclonus, photon, photonasty, photonegative, photoneutron, photonic, photonics

Origin of photon

First recorded in 1900–05; phot- + -on¹

Also called light quantum.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for photon

When the gamma rays enter the sleeve, they interact with that photon gas, annihilating into electron-positron pairs.
We Can Create Matter from Light?!|Matthew R. Francis|May 20, 2014|DAILY BEAST
The medicine worked because the photon–the quantum bundle of light and the carrier of the electromagnetic force–has no mass.
Finding Higgs Boson, or God Particle, Will Resolve Scientific Mysteries|Frank Close|December 17, 2011|DAILY BEAST
Among his pastimes was designing a solar-power car, the Photon Torpedo.
The Guy Who's Got $700 Billion of Your Money|Ross Goldberg|October 9, 2008|DAILY BEAST
"Well, you know what happens when a photon comes in contact with the atomic structure of matter," Kato said.
The Mercenaries|Henry Beam Piper

Or there may be an inelastic collision, when the photon hits an atom and knocks out an electron—the old photoelectric effect.
The Mercenaries|Henry Beam Piper
There were hundreds of scintillations, each caused by a nuclear particle or photon striking the screen.
The Blue Ghost Mystery|Harold Leland Goodwin
Or, the photon may be retained for a while and emitted again relatively unchanged—the effect observed in luminous paint.
The Mercenaries|Henry Beam Piper

British Dictionary definitions for photon

photon

/ (ˈfəʊtɒn) /

noun

a quantum of electromagnetic radiation, regarded as a particle with zero rest mass and charge, unit spin, and energy equal to the product of the frequency of the radiation and the Planck constant

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for photon

photon

"unit of electromagnetic radiation," 1926 in modern sense, from photo- "light" + -on "unit."

Medicine definitions for photon

photon

[ fō′tŏn′ ]

n.

The quantum of electromagnetic energy, generally regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime.

Related formspho•ton′ic adj.

Science definitions for photon

photon

[ fō′tŏn′ ]

The subatomic particle that carries the electromagnetic force and is the quantum of electromagnetic radiation. The photon has a rest mass of zero, but has measurable momentum, exhibits deflection by a gravitational field, and can exert a force. It has no electric charge, has an indefinitely long lifetime, and is its own antiparticle. See Note at electromagnetic radiation. See Table at subatomic particle.

Culture definitions for photon

photon

[ (foh-ton) ]

The quantum, or bundle of energy, in which light and other forms of electromagnetic radiation are emitted. (See atom.)