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

Currently, public-sector organizations in both countries remain light-years away from this model. —Greg Orme, Forbes, 11 Dec. 2024

This galaxy, roughly 59 million light-years away, is typical of the kinds of galaxies that inhabited the early universe and is classified as a dwarf irregular galaxy. —Alan Taylor, The Atlantic, 10 Dec. 2024

In 2025, the JWST will likely shed more light into these tantalizing detections, and hopefully confirm, for the first time ever, if there is life on alien worlds light-years away from our own. —Lisa Kaltenegger, WIRED, 5 Dec. 2024

Since the Sombrero Galaxy, at around 30 million light-years away, is visible with small telescopes, amateur astronomers have also taken interest, according to EarthSky’s Kelly Kizer Whitt. —Margherita Bassi, Smithsonian Magazine, 4 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