köken: From the Celtic period. Possibly attested in the Bern zinc tablet. Old hydronym usually separated as two elements (possibly through Celtic/Gaulish): * Proto-Indo-European *h₃er- (“to rise, stir, move”) * Proto-Indo-European *h₂wer- (“water, rain, flow”), found in cognates such as Sanskrit वार् (vār, “water, pond”), Latin urina, Lithuanian virti (“to seethe, boil, flow”), Old Norse vari (“water”).