At an average discharge of about 209,000 cubic metres per second (7,400,000 cu ft/s; 209,000,000 L/s; 55,000,000 USgal/s)—approximately 6,591 cubic kilometres per annum (1,581 cu mi/a), greater than the next seven largest independent rivers combined—the Amazon represents 20% of the global riverine discharge to the ocean. The Amazon basin is the largest drainage basin in the world, with an area of approximately 7,050,000 square kilometres (2,720,000 sq mi). The portion of the river's drainage basin in Brazil alone is larger than any other river's basin. The Amazon enters Brazil with only one-fifth of the flow it finally discharges into the Atlantic Ocean, yet already has a greater flow at this point than the discharge of any other river.
The river was initially known by Europeans as the Marañón and the Peruvian part of the river is still known by that name today. It later became known as the Rio Amazonas in Spanish and Portuguese, or The Amazon in English.
The word Amazon itself may be derived from the Iranian compound *ha-maz-an- "(one) fighting together" or ethnonym*ha-mazan- "warriors", a word attested indirectly through a derivation, a denominal verb in Hesychius of Alexandria's gloss "ἁμαζακάραν· πολεμεῖν. Πέρσαι" ("hamazakaran: 'to make war' in Persian"), where it appears together with the Indo-Iranian root *kar- "make" (from which Sanskritkarma is also derived).