light speed
Americannoun
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Physics, Optics. speed of light.
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an extremely fast rate.
The rumor circulated at light speed around the town.
adjective
Etymology
Origin of light speed
First recorded in 1855–60
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
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 ● Nov. 10, 2025
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 ● Nov. 3, 2025
And they can do it all at light speed.
From Los Angeles Times ● Nov. 6, 2023
The picture comes at you at light speed with so much information jampacked into every frame — visual, audio, emotional — that it needs to be seen more than once.
From Seattle Times ● Jun. 1, 2023
She drove fast and sang loudly, only looking at Luke when she took a turn at light speed and he instinctively grabbed the seat cushion below him.
From "We'll Fly Away" by Bryan Bliss
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
