Under ground

Related to Under ground: Underground hip hop
below the surface of the ground.

See also: Under

References in classic literature ?
And only have opening and windows towards the garden; and be level upon the floor, no whit sunken under ground, to avoid all dampishness.
And under these rooms, a fair and large cellar, sunk under ground; and likewise some privy kitchens, with butteries and pantries, and the like.
We laid it under ground, of course, and it was all finished in a couple of hours or so.