Old European hydronymyOld European (Alteuropäisch) is the term used by Hans Krahe (1964) for the language of the oldest reconstructed stratum of European hydronymy (river names) in Central and Western Europe. Krahe writes in A1, chapter III, "Introducing preface" Number 2 that the old European hydronomy extended from Scandinavia to South Italy, from Western Europe including the British Isles to the Baltic countries. Of the three Mediterranean peninsulas, Italy was most completely included, whilst the Balkan Peninsula was only scarcely covered.
DanubeThe Danube (ˈdæn.juːb ; ) is the second-longest river in Europe, after the Volga in Russia. It flows through much of Central and Southeastern Europe, from the Black Forest into the Black Sea. A large and historically important river, it was once a frontier of the Roman Empire and today connects ten European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , passing through or bordering Austria, Slovakia, Hungary, Croatia, Serbia, Romania, Bulgaria, Moldova, and Ukraine.
ToponymyToponymy, toponymics, or toponomastics is the study of toponyms (proper names of places, also known as place names and geographic names), including their origins, meanings, usage and types. Toponym is the general term for a proper name of any geographical feature, and full scope of the term also includes proper names of all cosmographical features. In a more specific sense, the term toponymy refers to an inventory of toponyms, while the discipline researching such names is referred to as toponymics or toponomastics.
Endonym and exonymAn endonym (also known as autonym) is a common, native name for a group of people, individual person, geographical place, language or dialect, meaning that it is used inside a particular group or linguistic community to identify or designate themselves, their homeland, or their language. An exonym (also known as xenonym) is an established, non-native name for a group of people, individual person, geographical place, language or dialect, meaning that it is used only outside the particular place inhabited by the group or linguistic community.