geyser

Etymology

From the name of a particular Icelandic geyser which is mentioned as early as the 1760s in The Annual Register, as “Geyser, a wonderful spring in the valley of Haukadal”. From Geysir (“Gusher”), the Icelandic name of the hot spring in Iceland (see Wikipedia), from the verb geysa (“to gush”), from Old Norse geysa (“to gush”). Doublet of gusher.

noun

1. (planetology, geology, volcanology) A boiling natural spring which throws forth jets of water, mud, etc., at frequent intervals, driven upwards by the expansive power of steam.
2. (by extension) A momentary vertical jet or fountain of fluid driven upwards by a violent force.
   Sporting a few war wounds from Japanese destroyer gunfire, The Sullivans had already launched one spread of torpedoes at the Japanese destroyers that were now littering the ocean floor, or, occasionally, making their own retreat, but she still had one left, so a five-torpedo spread was duly sent at near-point-blank range into the listing and burning remains of Yamato, and, shortly thereafter, four large geysers of water were the reward. 5 May 2021, Drachinifel, 42:03 from the start, in Battle of Samar - What if TF34 was there?, archived from the original on 2022-08-19
3. (Britain, archaic) An instantaneous, and often dangerous, hot water heater.
   Where a Geyser or hot-water heater is used it is a good and wise precaution to see that the bath-room, &c., when it is used is well ventilated. 1902, William Paton Buchan, Plumbing: A Text-book to the Practice of the Art Or Craft of the Plumber
   Water was heated either on the gas stove, or on a wall mounted gas-fired "geyser" heater. 1998, Gordon S Riess, Confessions of a Corporate Centurion: Tales of International Adventures
   It was here I saw a geyser gas water heater in a bathroom for the first time. (I was afraid of it). 2002, Alaine Polcz, One woman in the war: Hungary, 1944-1945
4. (South Africa, India) A domestic water boiler.

verb

1. (transitive, intransitive) To (cause to) rush or burst upward like water from a geyser.
   Four jets of water geysered upward from the sea. Short and wide. He noted it. Ranging salvo. His division was discovered. 1944, Jacland Marmur, Sea Duty: And Other Stories of Naval Action, page 21