light-year
nounUK /ˈlaɪt.jɪər/
US /ˈlaɪt.jɪr/
A light-year is how far light travels in one whole year, which is a very, very long distance.
The nearest star to our Sun is about four light-years away.
OTHER MEANINGS
2. A very long distance or a huge gap between things.
Their opinions were light-years apart.
3. A unit used by astronomers to measure distances between stars and galaxies.
The galaxy is 100,000 light-years across.
4. A long period of time, used figuratively.
It feels like a light-year since we last met.