Relating to or characteristic of geysers; of or pertaining to hot springs that erupt with boiling water and steam.
From geyser (Icelandic geysir, meaning 'gusher' or 'the one who gushes') plus the English adjectival suffix -al. The root word entered English from Icelandic when Europeans encountered Iceland's famous geysers.
Geysers were such a dramatic discovery for Europeans that Iceland's geothermal features actually gave English a completely new word! The Great Geyser in Iceland became so famous that all similar hot springs borrowed its name.
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