underworld

noun

1. the criminal element of human society.
2. the imagined abode of departed souls or spirits; Hades.
3. a region below the surface, as of the earth or a body of water.
4. the opposite side of the earth; the antipodes.
5. Archaic. the earth.

noun

1. 1. criminals and their associates considered collectively
   2. (as modifier)underworld connections
2. the regions below the earth’s surface regarded as the abode of the dead; Hades

n.c.1600, “the lower world, Hades,” also “the earth,” as distinguished from heaven. Cf. German unterwelt, Dutch onderwereld, Danish underverden. Meaning “lower level of society” is first recorded 1890; “criminals and organized crime collectively” is attested from 1900.