Wiktionary
a. beneath the surface of the ground; underground
WordNet
adj. under the level of the ground; "belowground storage areas"; "underground caverns" [syn: underground]
underneath the ground; "most of his friends are now belowground"
Usage examples of "belowground".
Those creaturs what lives belowground may be right bad, but leasts they leave behind what they don't eat.
It was bad enough on the groundbut belowground it was ratholes, with suffocating smells.
His preternaturally alert sense of hearing brought to his senses the presence of something belowground, something 'that moved and thumped, moved and thumped.
Edgar Hoover's former bomb shelter, an airless bunker belowground where pipes from the Academy's upper-level toilets sometimes leaked on worn carpet or ran in stinking trickles down cinder-block walls.