light year Meaning in the Cambridge English Dictionary
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Meaning of “light year” in the English Dictionary

"light year" in British English

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light yearnoun [C]

uk   us  
the ​distance that ​lighttravels in one ​year (about 9.5 million million ​kilometres)
(Definition of light year from the Cambridge Advanced Learner’s Dictionary & Thesaurus © Cambridge University Press)

"light year" in American English

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light yearnoun [C]

 us   /ˈlɑɪt ˌyɪər/
earth science the ​greatdistance 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 ​extremelylongdistance 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)
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