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light speed

light speed

8 5.0
The speed that light travels in empty space
  • noun
  • /laɪt spiːd/
  • Specialized
translation icon : velocidad de la luz
  • When traveling in space, nothing can exceed light speed, which is approximately 299,792,458 meters per second.

If so, it seems it would just be stuck at exactly light speed.

Examples

Synonyms

speed of light
vslight speed
  • Specialized
43 3.8

A constant speed at which light travels in empty space, about 300,000 kilometres per second

is the named expression rather than the raw numeric value
c
vslight speed
  • Specialized
9 7.7

The speed that light travels in empty space, exactly 299,792,458 meters per second

refers to the same constant by its full numeric or spelled out form
lightspeed
vslight speed
  • Specialized
2 4.9

The fastest speed at which light moves in empty space

gives the exact numeric definition without claiming maximum

Surface Forms

light speed singular
light speeds plural

Morphology

light + speed

The meaning 'the speed at which light travels' is directly and compositionally derived from 'light' (electromagnetic brightness) + 'speed' (how fast something moves), so a B1 learner who knows both words can infer the concept (i.e., 'speed of light'). This is a literal, cross-linguistically common scientific concept rather than an idiom, making the expression transparent.

Etymology

The phrase light speed comes from the idea of how fast light moves, with speed meaning how quickly something goes. Because light is the fastest thing we know, light speed means 'the highest possible speed' or is used to say something is 'very fast'.