Definition of "photon" [photon]

• 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. (noun)
• 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. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The measurement of the twin photon is intentionally delayed (8 nanoseconds) after the measurement of the signal photon."
• "Optimum antennae shape for both absorption and emission of a photon is a dipole FM antennae where the 2 opposing leads are set at the halfwave of desired cutoff."
• "Every detection of a photon is a measurement, resulting in the photon being observed just there."