A boiling spring which throws forth at frequent intervals jets of water, mud, etc., driven up by the expansive power of steam. [1913 Webster]
" Geysers were first known in Iceland, and later in New Zealand. In the Yellowstone region in the United States they are numerous, and some of them very powerful, throwing jets of boiling water and steam to a height of 200 feet. They are grouped in several areas called geyser basins. The mineral matter, or geyserite, with which geyser water is charged, forms geyser cones about the orifice, often of great size and beauty." [1913 Webster]

geyser, n.
1 an intermittently gushing hot spring that throws up a tall column of water.
2 Brit. an apparatus for heating water rapidly for domestic use.

Etymology:
Icel. Geysir, the name of a particular spring in Iceland, rel. to geysa to gush

N  river, running water, jet, spirt, spurt, squirt, spout, spray, splash, rush, gush, jet d'eau, sluice, water spout, water fall, cascade, force, foss, lin, linn, ghyll, Niagara, cataract, rapids, white water, catadupe, cataclysm, debacle, inundation, deluge, chute, washout, rain, rainfall, serein, shower, scud, downpour, driving rain, drenching rain, cloudburst, hyetology, hyetography, predominance of Aquarius, reign of St. Swithin, mizzle, drizzle, stillicidum, plash, dropping, falling weather, northeaster, hurricane, typhoon, stream, course, flux, flow, profluence, effluence, defluxion, flowing, current, tide, race, coulee, spring, artesian well, fount, fountain, rill, rivulet, gill, gullet, rillet, streamlet, brooklet, branch, runnel, sike, burn, beck, creek, brook, bayou, stream, river, reach, tributary, geyser, spout, waterspout, body of water, torrent, rapids, flush, flood, swash, spring tide, high tide, full tide, bore, tidal bore, eagre, hygre, fresh, freshet, indraught, reflux, undercurrent, eddy, vortex, gurge, whirlpool, Maelstrom, regurgitation, overflow, confluence, corrivation, wave, billow, surge, swell, ripple, anerythmon gelasma, beach comber, riffle, rollers, ground swell, surf, breakers, white horses, whitecaps, rough sea, heavy sea, high seas, cross sea, long sea, short sea, chopping sea, hydrodynamics, hydraulics, hydraulicostatics, rain gauge, flowmeter, pegology, irrigation, pump, watering pot, watering cart, hydrant, syringe, garden hose, lawn spray, bhisti, mussuk, fluent, diffluent, profluent, affluent, tidal, flowing, meandering, meandry, meandrous, fluvial, fluviatile, streamy, showery, rainy, pluvial, stillicidous, stillatitious, for men may come and men may go but I go on foreve, that old man river, he just keeps rolling along.

N  bubble; cloud, bubble, foam, froth, head, spume, lather, suds, spray, surf, yeast, barm, spindrift, cloud, vapor, fog, mist, haze, steam, geyser, scud, messenger, rack, nimbus, cumulus, woolpack, cirrus, stratus, cirrostratus, cumulostratus, cirrocumulus, mackerel sky, mare's tale, dirty sky, curl cloud, frost smoke, thunderhead, nephelognosy, nephograph, nephology, effervescence, fermentation, bubbling, nebula, cloudliness, nebulosity, bubbling, frothy, nappy, effervescent, sparkling, mousseux, frothy, up, cloudy, thunderheaded, vaporous, nebulous, overcast, the lowring element scowls o'er the darkened lands.

N  calefaction, increase of temperature, heating, calefaction, tepefaction, torrefaction, melting, fusion, liquefaction, burning, ambustion, combustion, incension, accension, concremation, cremation, scorification, cautery, cauterization, ustulation, calcination, cracking, refining, incineration, cineration, carbonization, cupellation, ignition, inflammation, adustion, flagration, deflagration, conflagration, empyrosis, incendiarism, arson, auto dafe, boiling, coction, ebullition, estuation, elixation, decoction, ebullioscope, geyser, distillation (vaporization), furnace, blanket, flannel, fur, wadding, clothing, still, refinery, fractionating column, fractionating tower, cracking tower, match, incendiary, petroleuse, cauterizer, caustic, lunar caustic, alkali, apozem, moxa, acid, aqua fortis, aqua regia, catheretic, nitric acid, nitrochloro-hydric acid, nitromuriatic acid, radioactivity, gamma rays, alpha particles, beta rays, X-rays, radiation, cosmic radiation, background radiation, radioactive isotopes, tritium, uranium, plutonium, radon, radium, sunstroke, coup de soleil, insolation, pottery, ceramics, crockery, porcelain, china, earthenware, stoneware, pot, mug, terra cotta, brick, clinker, cinder, ash, scoriae, embers, soot, slag, coke, carbon, charcoal, wood alcohol, turpentine, tea tree oil, gasoline, kerosene, naptha, fuel oil (fuel), wax, paraffin, residue, tar, inflammability, combustibility, diathermancy, transcalency, conduction, convection, radiation, radiant heat, heat conductivity, conductivity, thermal expansion, coefficient of expansion, heated, molten, sodden, r_echauff_e, heating, adust, inflammable, combustible, diathermal, diathermanous, burnt, volcanic, radioactive.