Astronomical Unit Definition

ăstrə-nŏmĭ-kəl

noun

A unit of length used in measuring astronomical distances within the solar system or other planetary system equal to the mean distance from Earth to the sun, approximately 150 million kilometers (93 million miles).

American Heritage

A unit of length based on the mean distance of the earth from the sun, c. 149.6 million km (c. 93 million mi): light travels this distance in c. 8.3 minutes: abbrev. AU.

Webster's New World

(astronomy) The mean distance from the Earth to the Sun (the semi-major axis of Earth's orbit), approximately 149,600,000 kilometres (symbol AU), used to measure distances in the solar system.

Wiktionary

Synonyms: