electromagnetic radiation (ee-LEK-troh-mag-NEH-tik ray-dee-AY-shun)
Radiation that has both electric and magnetic fields and travels in waves. It comes from natural and man-made sources. Electromagnetic radiation can vary in strength from low energy to high energy. It includes radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays. Also called EMR.