Where does “Дунай” come from?
Дунай (Russian) comes from Old East Slavic Дунаи, from Proto-Slavic Dunavь, from Gothic 𐌳𐍉𐌽𐌰𐍅𐌹, from Proto-Germanic Dōnawjaz, from Proto-Celtic Dānowyos, from Proto-Celtic Dānu, from Proto-Indo-European dʰenh₂- — to set in motion; to flow.
Дунай (Russian): Danube
Ancestry of “Дунай”, step by step