The speed at which light travels in a vacuum, approximately 186,282 miles per second, or something moving at extreme speed.
Compound of 'light' from Old English leoht and 'speed' from Old English sped meaning 'success, prosperity'. The scientific concept was formalized by Einstein's work in the early 20th century, making this word a bridge between ancient words and modern physics.
Lightspeed represents the universe's ultimate speed limit, but in popular culture it's become synonymous with impossibly fast travel between stars. It's fascinating that this fundamental constant of physics - something that can never be exceeded - has become our metaphor for the fastest possible action!
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