light-year

[lahyt-yeer, -yeer] /ˈlaɪtˌyɪər, -ˈyɪər/
noun
1.
Astronomy. 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.
Abbreviation: lt-yr.
2.
light-years.
  1. a very great distance, especially in development or progress:
    The new computer is light-years ahead of the old one.
  2. a very long time:
    It's been light-years since I've seen my childhood friends.
Origin
1885-90
Examples from the web for light year
  • That's something this franchise seemed a light year away from one calendar year ago.
  • Planetary nebulae, even large ones, are usually only a light year or two across.
  • Newt has a stack of baggage a light year tall and is volatile and untrustworthy.
British Dictionary definitions for light year

light year

noun
1.
a unit of distance used in astronomy, equal to the distance travelled by light in one year, i.e. 9.4607 × 1012 kilometres or 0.3066 parsecs
Word Origin and History for light year
n.

also light-year, lightyear, "distance light travels in one year," 1888, from light (n.) + year.

light year in Science
light-year
The distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). Light-years are used in measuring interstellar and intergalactic distances. Compare astronomical unit, parsec.

light year in Culture

light year definition


The distance traveled by light in a year (over five trillion miles); a unit for measuring distances outside the solar system. The star nearest to our sun, Alpha Centauri, is more than four light years away.