photon - a quantum of electromagnetic radiation; an elementary particle that is its own antiparticle

actinic radiation, actinic ray - electromagnetic radiation that can produce photochemical reactions

electron beam, ray, beam - a group of nearly parallel lines of electromagnetic radiation

black-body radiation, blackbody radiation - the electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law

Hertzian wave - an electromagnetic wave generated by oscillations in an electric circuit

gamma radiation, gamma ray - electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength

line - a single frequency (or very narrow band) of radiation in a spectrum

microwave - a short electromagnetic wave (longer than infrared but shorter than radio waves); used for radar and microwave ovens and for transmitting telephone, facsimile, video and data

radiation - energy that is radiated or transmitted in the form of rays or waves or particles

radio emission, radio radiation, radio wave - an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m

roentgen ray, X ray, X-radiation - electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target