photon

Term: photon

Literally meaning: “that carry light”

Origin: Anc Greek

φως/phos(=light) > (genitive φωτός/photos=of  light)

Coined/History

by Gilbert Lewis in 1926, though the concept of light in the form of discrete particles had been known.

Definition

1. (physics) photon is defined as a quantum of electromagnetic energy including light with  no mass or electric charge.  A photon has energy which is proportional to the frequency  of the radiation
2.  (biology) Photon is 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.