Dictionarylight-yearPronunciation: (līt'yēr", -yēr'), [key] —n. 1. Astron.the distance traversed by light in one mean solar year, about 5.88 trillion mi. (9.46 trillion km): used as a unit in measuring stellar distances. Abbr.: lt-yr 2. light-years, a. a very great distance, esp. in development or progress: The new computer is light-years ahead of the old one. b. a very long time: It's been light-years since I've seen my childhood friends. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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