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light-year

[ lahyt-yeer, -yeer ]
/ ˈlaɪtˌyɪər, -ˈyɪər /
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noun

Astronomy. the distance traversed by light in one mean solar year, about 5.88 trillion mi. (9.46 trillion km): used as a unit in measuring stellar distances. Abbreviation: lt-yr
light-years,
  1. a very great distance, especially in development or progress: The new computer is light-years ahead of the old one.
  2. a very long time: It's been light-years since I've seen my childhood friends.

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Nearby words

light-minded, light-o'-love, light-rail, light-sensitive, light-struck, light-year, lightboard, lightboat, lighten, lighten up, lightening

Origin of light-year

First recorded in 1885–90
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for light-year

Science definitions for light-year

light-year


The distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). Light-years are used in measuring interstellar and intergalactic distances. Compare astronomical unit parsec.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.