Meaning of “light year” in the English Dictionary

british dictionary

"light year" in British English

See all translations

(Definition of “light year” from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)

"light year" in American English

See all translations

light yearnoun [ C ]

us /ˈlɑɪt ˌyɪər/

earth science the great distance that light travels in one year; about 5,880,000,000,000 miles or 9,460,000,000,000 kilometers

earth science People sometimes say light years to talk about an extremely long distance or time:

When I was a young man, being 50 seemed light years away.

(Definition of “light year” from the Cambridge Academic Content Dictionary © Cambridge University Press)