water level

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The level of the surface of a body of water.
2. n. Geology See water table.
3. n. The water line of a ship.

Century Dictionary and Cyclopedia

1. n. In mining, a heading or gangway so nearly horizontal that drainage water in it flows very sluggishly or hardly at all.
2. n. The surface of the water in any vessel or reservoir, natural or artificial, in which water is standing, as in a well, canal, pond, lake, etc.; also, the plane of saturation beneath the surface of the ground, or the plane below which the soil or rock remains saturated with water under the ordinary conditions of rainfall, etc.
3. n. A leveling-instvument in which water is emploved instead of mercurv or spirit of wine. It consists of a tin tube, about 3 feet long, bent at right angles at each end, with a small short tube soldered on it at its center, by the aid of which it can be fixed upon some kind of a support or tripod. In the bent ends of the long tube are inserted two small glass vials with their bottoms out off. Enough water is then poured in to about half fill the bottles when the instrument is level. By sighting across the surface of the water a level-line is got. The extreme cheapness and portability of this level make it serviceable sometimes, although it gives but a rough approximation to accuracy as compared with the best kind of spirit-level.

Wiktionary

1. n. The level of a body of water, especially when measured above a datum line
2. n. The level of the water table below ground
3. n. The waterline of a ship

GNU Webster's 1913

1. n. an instrument to show the level by means of the surface of water in a trough, or in upright tubes connected by a pipe.
2. The level formed by the surface of still water.
3. A kind of leveling instrument. See under Level, n.

WordNet 3.0

1. n. underground surface below which the ground is wholly saturated with water
2. n. a line corresponding to the surface of the water when the vessel is afloat on an even keel; often painted on the hull of a ship
3. n. a water gauge that shows the level by showing the surface of the water in a trough or U-shaped tube
4. n. the level of the surface of a body of water