A river of Spain and Portugal. Rising in a plateau region south-east of Madrid, it flows south-westwards for some 580 km (360 miles), entering the Atlantic at the Gulf of Cadiz. For the last part of its course it forms the border between Spain and Portugal.
Definition of Guadiana in US English:
Guadiana
proper nounˌɡwädˈyänə
A river in Spain and Portugal. Rising in a plateau region southeast of Madrid, it flows southwest for about 350 miles (580 km) before entering the Atlantic Ocean at the Gulf of Cadiz. For the last part of its course, it forms the border between Spain and Portugal.