Definitions for light-year

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

WiktionaryRate this definition:(0.00 / 0 votes)

  1. light-year(Noun)

    An alternative spelling of light year.

FreebaseRate this definition:(0.00 / 0 votes)

  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.


Find a translation for the light-year definition in other languages:

Select another language:

Discuss these light-year definitions with the community:

Word of the Day

Would you like us to send you a FREE new word definition delivered to your inbox daily?

Please enter your email address:     


Use the citation below to add this definition to your bibliography:


"light-year." STANDS4 LLC, 2015. Web. 5 Mar. 2015. <>.

Are we missing a good definition for light-year? Don't keep it to yourself...

The Web's Largest Resource for

Definitions & Translations

A Member Of The STANDS4 Network

Nearby & related entries:

Alternative searches for light-year:

Thanks for your vote! We truly appreciate your support.