Danube 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. The river was known to the ancient Greeks as the "Istros" (Ἴστρος) a borrowing from a Daco-Thracian
Source of the Danube springs which differed in size or the starting point of a certain headwater also had a mythological meaning. This was reflected in holy springs/ water sanctuaries or in the worship of Naiads. This was also the case with the source of the mightiest river in the Roman Empire. The Danube river emanating from the Abnoba mountains was considered to be a river or spring goddess. In contrast to the more mythological role, the hydrological significance of the source of the Danube is uncommonly small. This is because the Danube gives an important part of its water to the Rhine both