water table

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The level below which the ground is completely saturated with water.
• noun A projecting ledge, molding, or stringcourse along the side of a building, designed to throw off rainwater.

from The Century Dictionary.

• noun In soil investigations, the upper surface of the gravitation or ground water; the upward limit of soil and rock saturation. See soil moisture.
• noun In car-building, a window ledge.
• noun In architecture, a string-course, molding, or other projecting member so placed as to throw off water from the wall of a building.
• noun A small embankment made across a road, especially on a hill, to carry off the water.
• noun Same as water-bridge.

from the GNU version of the Collaborative International Dictionary of English.

• (Arch.) A molding, or other projection, in the wall of a building, to throw off the water, -- generally used in the United States for the first table above the surface of the ground (see table, n., 9), that is, for the table at the top of the foundation and the beginning of the upper wall.
• (Hydraulic Engin.) The upper limit of the portion of the ground wholly saturated with water. The water table may be within a few inches of the surface or many feet below it.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geology The level, underground, below which the ground is saturated with water

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun underground surface below which the ground is wholly saturated with water