Danube

geographical name

Dan·​ube ˈdan-(ˌ)yüb 

variants or German Donau

ˈdō-ˌnau̇ 

or ancient Danubius

də-ˈnü-bē-əs 

da-,

-ˈnyü-

or Ister

ˈi-stər 

river 1770 miles (2848 kilometers) long in central and southeastern Europe flowing southeast from southwestern Germany into the Black Sea in Romania, with the northernmost channel forming the boundary between Romania and Ukraine

Danubian

da-ˈnyü-bē-ən 

adjective