light year

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[edit] English

[edit] Etymology

light + year

[edit] Noun

Wikipedia has an article on:

Wikipedia light year (plural light years)

  1. (astronomy) A unit of length (abbreviation ly; equal to just under 10 trillion kilometres (1016 metres)) equal to the distance light travels in one year; used to measure extremely large distances.
  2. (in plural light years; figurative, informal) A very long way.
    The marathon runner in the lead is light years ahead of the one at the back.
  3. (in plural light years; figurative, informal, nonstandard) A very long time.
    Some of Leonardo da Vinci’s inventions were light years ahead of their time.

[edit] Usage notes

  • The light year is a unit of length, but because it contains the word year 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.

[edit] Translations

astronomical distance

[edit] See also

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