Cavern. ++++ More often, just Cave - and the adjective "underground" is superfluous by noun's definition.
Below ground
crypt...textropolis
Subway
aquifer
inground
Superb is another word for excellent. Superb is another word for excellent.
Nilavara = underground cell of house
Another word for shake is "Tremble".
subterranean
Catacomb
aquifer
Crypt.
A Den. Cave. Underground lair
Souterrain Souterrain
Another word for the focus is the EPICENTRE (or if you are American the EPICENTER!) Of course the epicentre and focus are different in that one is on the ground and the focus is underground.
masking, screening, covering, going underground, veiling, suppressing, cloaking, out of sight, concealing.
By defintion, a tunnel is underground.
U N D to create the word 'underground' (UNDergroUND)
Underground is a 11 letter word starting with U and ending with D.
You can use the terms unearthing or digging up when saying something has been excavated. The word means that something was underground and then was unburied and brought out of the hole.