Danube is an Old European river name derived from a Proto-Indo-European *dānu. Other river names from the same root include the Dunaj, Dzvina/Daugava, Don, Donets, Dnieper, Dniestr, Dysna, Tana/Deatnu and Tuoni. In Rigvedic Sanskrit, dānu means "fluid, drop", and in Avestan, the same word means "river". In the Rigveda, Dānu once appears as the mother of Vrtra, "a dragon blocking the course of the rivers". The Finnish word for Danube is Tonava, which is most likely derived from the word for the river in Swedish and German, Donau. Its Sámi name Deatnu means "Great River". It is possible that dānu in Scythian as in Avestan was a generic word for "river": Dnieper and Dniestr, from Danapris and Danastius, are presumed to continue Scythian *dānu apara "far river" and *dānu nazdya- "near river", respectively.