astronomical unitastronomical unit
Astron. 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
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).