Water that exists in the lithosphere whether in the unsaturated or vadose zone, or the saturated zone.
water that has infiltrated soil to the root zone.
All water below the land surface, including soil moisture, capillary fringe water in the vadose zone, and ground water.
That water that is below the first layer of soil, turf-, etc., but cannot permeate any lower due to the tightness of the soil. (It is not part of the water table.) Sometimes referred to as ground water.
Water in the lithosphere, that is, below the ground surface.