Danube name meaning "strong, swift" (akin to Sanskrit "iṣiras" "swift"). In Latin, the Danube was variously known as ' or as '. The Dacian/Thracian name was "Donaris" for the upper Danube and "Istros" for the lower Danube. The Thraco-Phrygian name was "Matoas", "the bringer of luck". The Latin name is masculine, as are all its Slavic names, except Slovenian, (the name of the Rhine is also masculine in Latin, most of the Slavic languages, as well as in German). The German "Donau" (Early Modern German "Donaw, Tonaw", Middle High German "Tuonowe") is feminine, as it has been re-interpreted as containing the
Source of the Danube above and below Tuttlingen (see also Danube Sinkhole). As a consequence, it dries up most time of the year. Near Ulm, in terms of hydrology, the Danube gets a tributary to the Iller which is more water-rich. It even gets surpassed by the Inn. The Donaubach rises on the castle grounds near the left corner of the front face of the castle Donaueschingen in a karst spring. This karst spring has an embankment of 15 to 70 l/s and enters into the Brigach after flowing 90 meters belowground. The Brigach and the Breg become the Danube after 1.5 km. The