geyser

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A natural hot spring that intermittently ejects a column of water and steam into the air.
2. n. Chiefly British A gas-operated hot-water heater.

Century Dictionary and Cyclopedia

1. n. A spouting hot spring; a hot spring which projects water, either periodically or irregularly, to some height in the air. The Great Geyser of Iceland has been long known, and has given the name to phenomena of this character. This geyser spouts very irregularly, and sometimes throws a large volume of water to a height of nearly 100 feet. The height of the column is probably diminishing, as some old estimates make it much greater. There are numerous geysers in the Yellowstone region of the United States, some of which throw water to an elevation of 200 feet or more, and also on the North Island of New Zealand; and in the Napa valley of California are boiling springs that have been improperly called geysers. (See boiling spring, under boiling.) The true theory of the action of the Great Geyser of Iceland, and hence of geysers in general, was first established by Bunsen. The ejection of the water is caused by explosive action, due to the heating of the water, under pressure, in the lower part of the geyser-tube, to considerably above the boiling-point. The heated water acquires after a time elastic force sufficient to overcome the weight of the superincumbent water; and the relief from compression during the ascent is so great that steam is generated rapidly, and to such an amount as to eject violently from the tube a great quantity of the water.
2. n. A gas-burning apparatus attached to a bath for the purpose of heating water for the bath.

Wiktionary

1. n. planetology, geology, volcanology A boiling natural spring which throws forth at frequent intervals jets of water, mud etc., driven up by the expansive power of steam.
2. n. UK, archaic An instantaneous, and often dangerous, hot water heater using hot steam.
3. n. South Africa A domestic water boiler.

GNU Webster's 1913

1. n. A boiling spring which throws forth at frequent intervals jets of water, mud, etc., driven up by the expansive power of steam.

WordNet 3.0

1. n. a spring that discharges hot water and steam
2. v. to overflow like a geyser