hypogean, (high-puh-JEE-un) adj. Growing or living below the surface of the ground.

An interesting related word is hypogeum, n. The subterranean part of an ancient building, or an ancient underground burial chamber.

(from M-W)




p.s. Can anyone show me how to make pronunciation symbols? I have the ANSI codes, but they don't include a symbol for the schwa sound, among other things.