photon

n. elementary particle of light and electromagnetic energies

In physics, the photon is the elementary particle responsible for electromagnetic phenomena. It is the carrier of electromagnetic radiation of all wavelengths, including gamma rays, X-rays,  ultraviolet light, visible light, infrared light, microwaves, and radio waves. The photon differs from many other elementary particles, such as the electron and the quark, in that it has zero rest mass; therefore, it travels (in vacuum) at the speed of light, c. Like all quanta, the photon has both wave and particle properties (“wave–particle duality”). Photons show wave-like phenomena, such as refraction by a lens and destructive interference when reflected waves cancel each other out; however, as a particle, it can only interact with matter by transferring the amount of energy where h is Planck's constant, c is the speed of light, and is its wavelength. This is different from a classical wave, which may gain or lose arbitrary amounts of energy. For visible light the energy carried by a single photon is around a tiny  joules; this energy is just sufficient to excite a single molecule in a photoreceptor cell of an eye, thus contributing to vision.
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Noun
1. a quantum of electromagnetic radiation; an elementary particle that is its own antiparticle
(hypernym) gauge boson
(part-holonym) electromagnetic radiation, electromagnetic wave, nonparticulate radiation

(new spell.=Foton) photon, elementary particle of light and electromagnetic energies

n. photon, elementary particle of light and electromagnetic energies