Subterranean waters
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
Waters which lie wholly beneath the surface of the ground, and which either ooze and seep through the subsurface strata without pursuing any defined course or channel, (percolating waters.) or flow in a permanent and regular but invisible course, or lie under the earth in a more or less immovable body, as a subterranean lake.