light speed

American  

[lahyt speed] / ˈlaɪt ˌspid /

Or lightspeed

noun

1. Physics, Optics.  speed of light.

2. an extremely fast rate.

   The rumor circulated at light speed around the town.

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adjective

1. very fast.

   Her best time in the race is a lightspeed 8.7 seconds.

Etymology

Origin of light speed

First recorded in 1855–60

Example Sentences

That is swift on Earth but slow compared with winds near the Eddington limit around supermassive black holes, where outflows can reach 20 to 30 percent of light speed, more than 200 million km/h.

From Science Daily

Beyond a certain point—roughly 800 square millimeters, or 1.25 square inches—the laws of light and light speed prohibit larger designs.

From The Wall Street Journal

A nearby, highly magnetized white dwarf could accelerate those particles to near–light speeds.

From Science Magazine

But at light speed, with a mass audience and a permanent record.

From Los Angeles Times

Quakes rupture on a fault at the speed of sound through rock, which is slower than the light speed of today’s telecommunications systems.

From Los Angeles Times