Geysir

As defined by the Cleasby & Vigfusson Old Norse to English dictionary:

geysir

m. the name of a famous hot spring in Iceland. Foreign writers often use geysir as an appellative; but the only Icel. words for hot springs are hver (a cauldron, hot well) and laug (a hot bath). The present Geysir is never mentioned in old writers, and it seems from a record in the Icel. Annals that the great hot wells in the neighbourhood of Haukadale were due to the volcanic eruptions of 1294, when old hot springs disappeared and those now existing came up,—hjá Haukadal kómu upp hverir stórir en sumir hurfu þeir er áðr höfðu verit; unfortunately the end of Árna S. (the bishop), the sole historical work of that time, is lost. The word geysir = a gusher must be old, as the inflexive -ir is hardly used but in obsolete words (læknir a leach, hellir a cave, etc., are exceptional); it was probably borrowed from some older hot spring. A pretty legend, referring to the ‘moving’ of springs when defiled with innocent blood, is recorded in Ísl. ÞjóðS. ii. 112, 113; this tale could not have sprung up unless a change in the place of the hot springs had been observed.

Possible runic inscription in Younger Futhark:ᚴᛁᚢᛋᛁᚱ
Younger Futhark runes were used from 8th to 12th centuries in Scandinavia and their overseas settlements