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,

a very great distance, especially in development or progress: The new computer is light-years ahead of the old one.
a very long time: It's been light-years since I've seen my childhood friends.

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Origin of light-year

First recorded in 1885–90

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use light-year in a sentence

However, more than 20 players on the ballot this year were probably worthy of being enshrined in Cooperstown.
Conservative Curt Says His Politics, Not His Pitching, Kept Him Out of the Hall of Fame|Ben Jacobs|January 9, 2015|DAILY BEAST
The influential al Qaeda propagandist, who was born in New Mexico, died in a U.S. drone strike later that year.
France Kills Charlie Hebdo Murderers|Nico Hines|January 9, 2015|DAILY BEAST
Eric Garcetti succeeded Villaraigosa and has received high marks in his first year and a half on the job.
The Golden State Preps for the ‘Red Wedding’ of Senate Races|David Freedlander|January 9, 2015|DAILY BEAST
Grindr introduced the feature themselves in October the same year and called it ‘tribes.’
Grindr’s Trans Dating Problem|David Levesley|January 9, 2015|DAILY BEAST

In the last year, her fusion exercise class has attracted a cult following and become de rigueur among the celebrity set.
How Taryn Toomey’s ‘The Class’ Became New York’s Latest Fitness Craze|Lizzie Crocker|January 9, 2015|DAILY BEAST
In the year of misery, of agony and suffering in general he had endured, he had settled upon one theory.
The Homesteader|Oscar Micheaux
Behold a dumpy, comfortable British paterfamilias in a light flannel suit and a faded sun hat.
God and my Neighbour|Robert Blatchford
She did not need a great cook-book; She knew how much and what it took To make things good and sweet and light.
Boys and Girls Bookshelf; a Practical Plan of Character Building, Volume I (of 17)|Various
Mr. Jones swung round a large iron key he held in his hand, and light dawned upon him.
Elster's Folly|Mrs. Henry Wood
Distance, the uncertain light, and imagination, magnified it to a high wall; high as the wall of China.
The Giant of the North|R.M. Ballantyne

British Dictionary definitions for light-year

light year

noun

a unit of distance used in astronomy, equal to the distance travelled by light in one year, i.e. 9.4607 × 10 12 kilometres or 0.3066 parsecs

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific 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.

Cultural definitions for light-year

light year

The distance traveled by light in a year (over five trillion miles); a unit for measuring distances outside the solar system. The star nearest to our sun, Alpha Centauri, is more than four light years away.