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Definition of photon - 6 dictionary results

pho⋅ton

  [foh-ton]
Use photon in a Sentence
–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
Also called light quantum.

Origin:
1900–05; phot- + -on 1
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
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pho·ton   (fō'tŏn')   
n.  

  1. The quantum of electromagnetic energy, regarded as a discrete particle having zero mass, no electric charge, and an indefinitely long lifetime. See Table at subatomic particle.

  2. A unit of retinal illumination, equal to the amount of light that reaches the retina through 1 square millimeter of pupil area from a surface having a brightness of 1 candela per square meter.

pho·ton'ic adj.
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2009 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Cultural Dictionary

photon [(foh-ton)]

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

The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Word Origin & History

photon 
"unit of electromagnetic radiation," 1926, from photo- "light" + on "unit."
Online Etymology Dictionary, © 2001 Douglas Harper
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Medical Dictionary

Main Entry: pho·ton
Pronunciation: 'fO-"tän
Function: noun
1 : a unit of intensity of light at the retina equal to the illuminationreceived per square millimeter of a pupillary area from a surface having a brightness of one candle per square meter called also troland
2 : a quantum of electromagneticradiation
Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
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Medical Dictionary

photon pho·ton (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.

pho·ton'ic adj.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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