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

Proxima is about four light-years away; the Milky Way is about 100,000 light-years in diameter. —Jacob Wilde, Scientific American, 17 July 2024

For comparison, the Andromeda Galaxy is the Milky Way’s closest neighbor at roughly 2.5 million light-years away. —Sarah Kuta, Smithsonian Magazine, 15 July 2024

This planetary system is about 41 light-years away, within our own galaxy and virtually next door in the cosmic scheme of things. —Joel Achenbach, Washington Post, 12 July 2024

The James Webb Space Telescope recently spotted evidence that a planet over 48 light-years away is home to a liquid water ocean. —Michael Kan, PCMAG, 9 July 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