Definitions for light-year

This page provides all possible meanings and translations of the word light-year

Random House Webster's College Dictionary


  1. 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.

    Category: Astronomy

  2. light-years, a very great distance, esp. in development or progress: a very long time.

    Today's computers are light-years ahead of older ones.

    Category: Common Vocabulary

Origin of light-year:



  1. light-year(Noun)

    An alternative spelling of light year.


  1. Light-year

    A light-year, also light year or lightyear, is an astronomical unit of length equal to just under 10 trillion kilometres. As defined by the International Astronomical Union, a light-year is the distance that light travels in a vacuum in one Julian year. The light-year is mostly used to express distances to stars and other distances on a galactic scale, especially in non-specialist and popular science publications. The preferred unit in astrometry is the parsec, because it can be more easily derived from, and compared with, observational data. Note that the light-year is a measure of distance. It is not a measure of time, for which it is sometimes mistaken.

Translations for light-year

Kernerman English Multilingual Dictionary


the distance light travels in a year (nearly 9.5 million million kilometres).

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