light year

 

English Wikipedia has an article on:

light year

Wikipedia

• lightyear, light-year

• (Received Pronunciation) IPA^(key): /ˈlaɪt.jɪə/
• (General American) enPR: lītyîr, IPA^(key): /ˈlaɪt.jɪɹ/
• (General South African) IPA^(key): /ˈläːt.jøː/
• (Wales, other regions) IPA^(key): /ˈlaɪt.jɜː/

• Audio (US):

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light year (plural light years)

2. (astronomy) A unit of length (abbreviation ly; equal to just under 10 trillion kilometres (10¹⁶ metres)) equal to the distance light travels in one Julian year; used to measure extremely large distances.
   • 2012 January, Robert L. Dorit, “Rereading Darwin”, in American Scientist‎^[1], volume 100, number 1, archived from the original on 14 November 2012, page 23:

     We live our lives in three dimensions for our threescore and ten allotted years. Yet every branch of contemporary science, from statistics to cosmology, alludes to processes that operate on scales outside of human experience: the millisecond and the nanometer, the eon and the light-year.

3. (only in plural, figurative, informal) A very long way.

   The marathon runner in the lead is light years ahead of the one at the back.

   • 2024 May 10, Hannah Oh, Daisy Maldonado, “50 College Graduation Gifts That Say, “I’m So Effing Proud of You!””, in Cosmopolitan‎^[2]:

     Now that they've graduated, they'll have to make some mature decisions in their future. One of which? Settling on their signature scent that is lightyears away from the $10 body spray they had throughout school.

4. (only in plural, figurative, informal) A very long time.

   Some of Leonardo da Vinci’s inventions were light years ahead of their time.

• The light year is a unit of length, but because it contains the word year, it is sometimes assumed to be a unit of time. Its use in the figurative sense of "a very long time" is nonstandard; it is preferable to use an alternative term in this case.
• light year and light-year are similarly common overall, lightyear lagging far behind.^[1][2] light-year leads in the American corpus while light year leads in the British corpus.^[1][2] GPO manual favors light-year.^[3] Merriam-Webster has light-year.^[4] OED has light year.^[5]

• “light year”, in OneLook Dictionary Search.