Meaning

noun a spring that discharges hot water and steam

verb to overflow like a geyser

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

Etymology from Wiktionary, CC BY-SA 3.0