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).Neutrinos are ghostly particles that can travel through a light year of lead and they have no problem escaping directly from the core of a supernova....
- If a star exploded a light year away, the increased cosmic ray intensity could have killed the animals by giving them all an intense dose of radiation.
- A light year is a convenient means of distance measurement because conventional means in miles or kilometers is so large as to thwart true appreciation.
1.1 (light years) informal A long distance or great amount: the new range puts them light years ahead of the competition...
- Defensively, they are light years ahead of where they were last season.
- In some ways, there are breeds of gull and sea bird who are light years ahead of us on the long-term commitment front and don't seem to have the same issues that we do.
- The standard of director to be found in the country's boardrooms is light years ahead of the small - town businessmen who formerly ruled the roost.