light year

/ˈlaɪt ˌjɪr/
noun
  1. A unit of distance equal to the distance light travels in one year (about 5.88 trillion miles or 9.46 trillion kilometers), used to measure vast distances in space.
    • A light-year is a measure of distance, not time, even though it contains the word 'year.'
    • Astronomers discovered a new galaxy that is 10 billion light-years from our solar system.
    • The nearest star to Earth, Proxima Centauri, is about 4.2 light-years away.
  2. A very large amount or degree of difference, often used in comparisons.
    • Her new computer is light-years ahead of her old one in speed.
    • Modern medicine has advanced light-years beyond what was available a century ago.
    • The team's performance this season is light-years better than last year.
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