The river Drava or Drau.
river in SC Europe, flowing from the Alps of Austria southeastward through Slovenia & Croatia into the Danube: c. 450 mi (724 km)
or Dra·ve also Drau
A river rising in the Carnic Alps of southern Austria and flowing about 725 km (450 mi) eastward through Slovenia and northern Croatia to the Danube River.
From historical Dravus, itself of unknown origin - either Celtic or Old European.