astronomical unit Word Origin noun Astronomy.
- a unit of length, equal to the mean distance of the earth from the sun: approximately 93 million miles (150 million km). Abbreviation: AU
Origin of astronomical unit First recorded in 1900–05 British Dictionary definitions for astronomical unit astronomical unit noun
- a unit of distance used in astronomy equal to the mean distance between the earth and the sun. 1 astronomical unit is equivalent to 1.495 × 10 11 metres or about 9.3 × 10 7 miles
astronomical unit in Science astronomical unit [ăs′trə-nŏm′ĭ-kəl]
- A unit of length equal to the average distance from Earth to the Sun, approximately 149.6 million km (92.8 million mi). It is used especially to measure distances within the solar system. Compare light-year parsec.
astronomical unit in Culture astronomical unit