noun

lightspeed

LYT-speed

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Lightspeed (noun) means the speed at which light travels, usually through a vacuum. Example: “The probe's onboard computer calculated the signal delay at lightspeed.”

noun

The speed at which light travels, usually through a vacuum.

"The probe's onboard computer calculated the signal delay at lightspeed."

"No spacecraft in the story could travel faster than lightspeed."

"Scientists measure lightspeed precisely in laboratory experiments."

colloquial A very high speed, used to describe something moving or happening extremely quickly.

"The news spread across the office at lightspeed."

"She finished the report at lightspeed before the meeting started."

"Prices in that market seem to change at lightspeed."

How to use lightspeed

Learner’s notes

In plain EnglishLightspeed means the speed light travels at, or, loosely, anything that happens very fast.

When to use it

The figurative sense is informal and suits everyday or conversational writing rather than formal scientific text.

Memory tip

Use the literal sense in scientific contexts and the figurative sense when you simply mean very fast.

Trace the full origin ↓

Common pairings

travel at lightspeed faster than lightspeed at lightspeed approach lightspeed

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C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

Test yourself on “lightspeed” A quick quiz — meaning, synonyms & usage →

Fill the gap

Can you complete this real example?

The probe's onboard computer calculated the signal delay at _____.

Etymology

Formed within English by combining the word light with the word speed. The compound describes the rate at which light travels and, by extension, any comparably fast rate.

Origin: English

Synonyms

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speed of light

Rhymes for lightspeed

feed seed reed deed need heed weed peed bleed breed speed creed

See all rhymes for lightspeed →

Frequently asked questions

What does lightspeed mean?

It refers to the speed of light, or informally to something happening extremely fast.

Is lightspeed one word or two?

It is commonly written as one word, lightspeed, though light speed as two words is also used.

Can lightspeed be used figuratively?

Yes, it is often used colloquially to describe something that happens or moves very quickly, not literally at the speed of light.

What is the meaning of lightspeed?

"lightspeed" (noun) means the speed at which light travels, usually through a vacuum.