Lewis Short
(adjective) = ὑπόγαιος: hypŏgēus, a, um
* Underground: loca,Cael. Aur. Tard. 2, 37, 191.—Hence, subst.: hypŏgēum or hy-pŏgaeum, i, n., = ὑπόγειον (ὑπόγαιον), a vault or cellar under ground, Vitr. 6, 11; a burying-vault, sepulchre, Petr. 111, 2; Inscr. Grut. 1114, 3.
Charlton T. Lewis, Charles Short, A Latin Dictionary