light-year
UK: ˈlaɪt jɪə | US: ˈlaɪt jɪr
n. a unit of astronomical distance equivalent to the distance that light travels in one year (approx. 9.46 trillion kilometers)
n. (figuratively) an immense or immeasurable span
The term "light-year" combines "light" (from Old English lēoht, meaning "visible radiation") and "year" (from Old English gēar, meaning "time unit"). Coined in the mid-19th century, it reflects the logical fusion of physics (light's speed) and astronomy (cosmic distances). The word's structure directly mirrors its scientific purpose: measuring vast interstellar space by the distance light covers in a Earth-year timeframe.
Proxima Centauri is about 4.24 light-years from Earth.
The galaxy is millions of light-years away.
His knowledge of history spans light-years beyond mine.
Scientists use light-years to map the universe's scale.
The concept of a light-year helps us grasp cosmic enormity.