light-year

noun
\ ˈlīt-ˌyir How to pronounce light-year (audio) \

Definition of light-year

1 : a unit of length in astronomy equal to the distance that light travels in one year in a vacuum or about 5.88 trillion miles (9.46 trillion kilometers)
2 : an extremely large measure of comparison (as of distance, time, or quality) seems like light-years ago has light-years more talent two minutes and yet light-years away from the crowded village— Suzanne Patterson

Synonyms for light-year

Synonyms

galaxy, world

Visit the Thesaurus for More 

First Known Use of light-year

1867, in the meaning defined at sense 1

Keep scrolling for more

Learn More about light-year

Statistics for light-year

Look-up Popularity

Time Traveler for light-year

The first known use of light-year was in 1867

See more words from the same year

Keep scrolling for more

More Definitions for light-year

light-year

noun

English Language Learners Definition of light-year

technical : a unit of distance equal to the distance that light travels in one year (about 5.88 trillion miles or 9.46 trillion kilometers)
used to say that someone or something is much better or more advanced than others
used to refer to a time that is or seems very far away

light-year

noun
\ ˈlīt-ˌyir\

Kids Definition of light-year

: a unit of length in astronomy equal to the distance that light travels in one year or about 5.88 trillion miles (9.46 trillion kilometers)

Keep scrolling for more

Comments on light-year

What made you want to look up light-year? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

a device or gadget

Get Word of the Day daily email!

Test Your Vocabulary

Words for Summer: A Quiz

  • a closeup of a sunflower
  • Which of the following words means “of or relating to summer”?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!

TAKE THE QUIZ
Dictionary Devil

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!