Definitions for "Electromagnetic spectrum"
the entire range of radiation extending in frequency from approximately 1023 hertz to 0 hertz or, in corresponding wavelengths, from 10-13 centimeter to infinity and including, in order of decreasing frequency, cosmic ray photons, gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, microwaves, and radio waves. It has many uses due to the speed at which it propagates (the speed of light) and because it can be used to transmit great deals of energy or very little (such as radio waves which are virtually harmless at low amplitude).
The frequencies present in a given electromagnetic radiation. A particular spectrum could include a single frequency or a wide range of frequencies.
A spectrum of wave energy that includes: radio, television, radar, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays, and cosmic rays.