light speed

Thesaurus

Noun

1.

light speed - the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per secondspeed of light, cconstant - a number representing a quantity assumed to have a fixed value in a specified mathematical context; "the velocity of light is a constant"speed, velocity - distance travelled per unit time