Is it ensure, insure, or assure?
of troops, by 1991, in reference to the end of the Cold War; from draw (v.) + down (adv.). Earlier of wells (c.1900).
A lowering of the water level in a reservoir or other body of water, especially as the result of withdrawal.
The difference in elevation between the level of water in a well and the level of groundwater in the area in which the well is located.