Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English

English definition of “light year”

light year

noun [C] uk   us  
the distance that light travels in one year (about 9.5 million million kilometres)Years and yearlyMeasurements in general
(Definition of light year from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
What is the pronunciation of light year?
Add Cambridge dictionaries to your browser to your website

Definitions of “light year” in other dictionaries

Translations of “light year”

Word of the Day

scrumpy

an alcoholic drink made from apples

Word of the Day

Blog

Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More