astronomical (adj.)youdaoicibaDictYouDict[astronomical 词源字典]
1550s, from astronomy + -ical. Popular meaning "immense, concerning very large figures" (as sizes and distances in astronomy) is attested from 1899. Astronomical unit (abbreviation A.U.) "mean distance from Earth to Sun," used as a unit of measure of distance in space, is from 1909. Related: Astronomically.[astronomical etymology, astronomical origin, 英语词源]