waterspout

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A tornado or lesser whirlwind occurring over water and resulting in a funnel-shaped whirling column of air and spray.
2. n. A hole or pipe from which water is discharged.

Century Dictionary and Cyclopedia

1. n. A pipe, nozle, or orifice from which water is spouted.
2. n. A spout, jet, or column of water; specifically, a whirlwind over a body of water, producing the appearance of a solid column of water extending from the surface to the clouds. In reality, however, the phenomenon that is seen is the cloud brought down to the earth's surface by the rapid gyratory motion of a vertical whirl, and it consists simply of fine mist surrounding a central axis of rarefaction. At first the cloud has the form of a tapering funnel; then, descending to near the water's surface, it draws up the water for a distance into its vortex, and imparts to it its whirling motion. The spout is then complete, and appears as an immense column connecting sea and cloud, light in color near the center, but dark along the sides. Like other whirlwinds, the waterspout has a progressive as well as a rotary motion, its axis sometimes being inclined forward in the direction of advance. After continuing a short time, generally less than twenty minutes, the column is disunited, the lower part descending as rain, while the upper part is drawn back into the clouds. The height of the spout depends upon the hygrometric state of the air; iu general it is between 800 and 2,500 feet. It is common for a number of waterspouts to be seen simultaneously or successively; and this is to be expected, for a series of separate and independent gyrations are likely to arise when the air is in a state of instability, such as is required for the development of these whirlwinds. This is especially the case in tropical and equatorial regions, where waterspouts are most frequent.

Wiktionary

1. n. a tornado that occurs over a body of water
2. n. a channel through which water is discharged, especially from the gutters of a roof

GNU Webster's 1913

1. n. A remarkable meteorological phenomenon, of the nature of a tornado or whirlwind, usually observed over the sea, but sometimes over the land.

WordNet 3.0

1. n. a tornado passing over water and picking up a column of water and mist
2. n. a channel through which water is discharged (especially one used for drainage from the gutters of a roof)
3. n. a heavy rain