light-year: Meaning and Definition of

light-year

1. 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. The new computer is light-years ahead of the old one.
1. a very great distance, esp. in development or progress:The new computer is light-years ahead of the old one.
2. a very long time:It's been light-years since I've seen my childhood friends.