light year
noun
1- Astronomy a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607×1012 km (nearly 6 million million miles)【天文】光年。
1.1
light years
informal a long distance or great amount〈非正式〉远距离; 大量：the new range puts them light years ahead of the competition.
新产品系列让他们在竞争中遥遥领先。