Pronunciation: ' l ī t- ˌ yir
Function: noun
Date: 1888
1 : a unit of length in astronomy equal to the distance that light travels in one year in a vacuum or about 5.88 trillion miles (9.46 trillion kilometers)
2 : an extremely large measure of comparison (as of distance, time, or quality) <seems like light-year s ago> <has light-year s more talent> <two minutes and yet light-year s away from the crowded village ― Suzanne Patterson>