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.
Think of it like evolution on steroids—billions of years happening at light speed within vast AI supercomputers.
From The Wall Street Journal ● Sep. 16, 2026
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
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 ● Jun. 5, 2024
To give a sense of scale, it would take a spaceship travelling at light speed a little over four years to traverse the entire scene.
From BBC ● Oct. 2, 2023
Traveling at light speed, it would take me just over fifteen minutes to reach Frobozz.
From "Ready Player One: A Novel" by Ernest Cline
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Get a wordDefinitions 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.
