: the form of energy that makes it possible to see things : the brightness produced by the sun, by fire, a lamp, etc.
: a source of light (such as an electric lamp)
: a light on a vehicle
Full Definition of LIGHT
a: something that makes vision possible
b: the sensation aroused by stimulation of the visual receptors
c: electromagnetic radiation of any wavelength that travels in a vacuum with a speed of about 186,281 miles (300,000 kilometers) per second; specifically: such radiation that is visible to the human eye