belowground

[ bih-loh-ground ]
/ bɪˈloʊˌgraʊnd /

adjective

situated beneath the surface of the earth; subterranean.
no longer living; buried, as in a cemetery (usually used predicatively): All those who might have known about the incident are now belowground.

Origin of belowground

First recorded in 1955–60; below + ground1