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
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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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use light-year in a sentence
One magnetar is only about a light-year from the black hole at the center of the Milky Way.
One could imagine falling forty-two thousand miles, where one couldn't imagine falling a light-year.Pariah Planet | Murray Leinster
That expedition perished after less than a light-year when its hydroponics system failed.Control Group | Roger Dee
But this monster—a thing now as big as the whole Solar System doubtless—was speeding through a light-year in a moment!The World Beyond | Raymond King Cummings
"The distance is half a light-year now, sir," reported the navigation officer.The Ultimate Weapon | John Wood Campbell
In popular writings, another unit: a light-year, has for a very long time been employed.Lectures on Stellar Statistics | Carl Vilhelm Ludvig Charlier
British Dictionary definitions for light year
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
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.
Cultural definitions for light year
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.