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

It’s also considered to be a nearby star at a little over 36 light-years away. —Mike Lynch, Twin Cities, 13 Apr. 2025

The researchers also pinpointed the light to a Milky Way star about 12,000 light-years away from Earth. —Meghan Bartels, Scientific American, 11 Apr. 2025

The astronomers' discovery marks the first such 1a supernova-causing binary system ever identified, and just about 150 light-years away from Earth—which on the scale of the universe, is actually quite close. —Margherita Bassi, Smithsonian Magazine, 9 Apr. 2025

What is alleged doesn't come within light-years of a violation of any FCC policy. —ArsTechnica, 7 Apr. 2025

Word History

First Known Use

1864, in the meaning defined at sense 1

Rhymes for light-year

• atmosphere
• biosphere
• centromere
• chemosphere
• chromosphere
• hemisphere
• hydrosphere
• lithosphere
• mesosphere
• microsphere
• miserere
• mountaineer

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