photon

Meaning

Noun

• The quantum of light and other electromagnetic energy, regarded as a discrete particle having zero rest mass, no electric charge, and an indefinitely long lifetime. It is a gauge boson.

Origin

• From photo- + -on. as a unit of light hitting the retina, and later popularized in a more modern sense by Gilbert N. Lewis, with the term gaining acceptance in the physics community by the late 1920s.