light-year

noun

ˈlīt-ˌyir 

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-years ago

has light-years more talent

two minutes and yet light-years away from the crowded village

—Suzanne Patterson

Synonyms

• galaxy
• world

Examples of light-year in a Sentence

my sister and I are close in age, but personality-wise, there are light-years between us

Recent Examples on the Web

Located roughly 150 million light-years from Earth in the constellation Serpens, UGC 10043 is one of the somewhat rare spiral galaxies that are seen edge-on. —Alan Taylor, The Atlantic, 22 Dec. 2024

Late last year, two of the most powerful space telescopes in the universe joined forces to highlight colorful galaxy clusters about 4.3 billion light-years away from Earth. —Laura Baisas, Popular Science, 20 Dec. 2024

The planet lies in a globular cluster, Messier 4, over 6,000 light-years from Earth. —Keith Cooper, Space.com, 20 Dec. 2024

Geminid meteor shower peaks in spectacular show Within the scope of that research, Jansky discovered Sagittarius A*, a supermassive black hole about 26,000 light-years from Earth. —Julia Jacobo, ABC News, 17 Dec. 2024

Word History

First Known Use

1864, in the meaning defined at sense 1

Kids Definition

light-year

noun

ˈlīt-ˌyi(ə)r

1

: a unit of length in astronomy equal to the distance that light travels in one year or 5,880,000,000,000 miles (9,460,000,000,000 kilometers)

2

: a very great distance especially in progress

light-years ahead in design