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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
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First Known Use of light–year
1867
LIGHT–YEAR Defined for English Language Learners
light-year
playDefinition of light–year for English Language Learners
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: a unit of distance equal to the distance that light travels in one year (about 5.88 trillion miles or 9.46 trillion kilometers)
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light-years —used to say that someone or something is much better or more advanced than others
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—used to refer to a time that is or seems very far away
LIGHT–YEAR Defined for Kids
light–year
playDefinition of light–year for Students
: 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)
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See words that rhyme with light–year Spanish Central: Translation of light–year
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