Underworld
来自Big Physics
wiktionary
under- + world
etymonline
underworld (n.)
c. 1600, "the lower world, Hades, place of departed souls," also "the earth, the world below the skies," as distinguished from heaven. Similar formation in German unterwelt, Dutch onderwereld, Danish underverden. Meaning "lower level of society" is first recorded 1890; "criminals and organized crime collectively" is attested from 1900.
