light year

Từ điển Oxford Advanced Learner 8th

ˈlight year [light year light years] BrE NAmE noun
1. (astronomy)the distance that light travels in one year, 9.4607 × 10 12 kilometres
•The nearest star to earth is about 4 light years away.
2. light yearsplural a very long time
•Full employment still seems light years away.