1 noun, adjective, -er, -est, verb, light·ed or lit, light·ing.
2. Physics .
a. Also called luminous energy, radiant energy. electromagnetic radiation to which the organs of sight react, ranging in wavelength from about 400 to 700 nm and propagated at a speed of 186,282 mi./sec (299,972 km/sec), considered variously as a wave, corpuscular, or quantum phenomenon.
15. Art .
a. the effect of light falling on an object or scene as represented in a picture.
b. one of the brightest parts of a picture.