the area around the River Amazon in South America, principally in Brazil, but also extending into Peru, Colombia, and Bolivia. The region comprises approximately one third of the world’s remaining tropical rainforest.
a national park protecting 10,000 sq. km (3,850 sq. miles) of tropical rainforest in the state of Pará, northern Brazil.
Amazonia in other Oxford dictionaries
Definition of Amazonia in the US English dictionary