gey·ser 
(gīzər)
(gīzər)n.
1. A natural hot spring that intermittently ejects a column of water and steam into the air.
2. (gēzər) Chiefly British A gas-operated hot-water heater.
[After Icelandic Geysir, name of a hot spring of southwest Iceland, from geysa, to gush, from Old Norse; see gheu- in the Appendix of Indo-European roots.]
geyserWater contained in porous rock seeps into an opening. Heated by magma below, it escapes under pressure to the earth's surface.