Word.ws English Dictionary

light years

light years is the plural of light year.

Meaning of light year

Noun

light year (plural light years, abbreviation ly)

  1. A unit of length used to measure extremely large distances, equal to approximately 9.46 trillion kilometres 10 trillion kilometres (10¹⁶ metres), equivalent to the distance light travels in one Julian year.
    • 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.2012 January, Robert L. Dorit, “Rereading Darwin”, in American Scientist, volume 100, number 1, archived from the original on 14 Nov 2012, retrieved 11 May 2013-05-11, page 23
  2. (figuratively, in plural, informal) A very long way.
    • The marathon runner in the lead is light years ahead of the one at the back.
  3. (figuratively, in plural, informal) A very long time.
    • Some of Leonardo da Vinci’s inventions were light years ahead of their time.

Questions about light years

What is light years the plural of?
Light years is the plural of light year.

Words near light years in the dictionary

  1. light waves
  2. Light Web
  3. light week
  4. light weeks
  5. light year
  6. light years
  7. light æon
  8. light æons
  9. light-bearing
  10. light-bulb
  11. light-bulb moment

Source and license

Adapted from Wiktionary: light years (page history and authors); light year (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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Cite this entry: “light years.” Word.ws, https://word.ws/light_years. Based on Wiktionary, CC BY-SA 4.0.