Amazon (n.)
late 14c., from Greek Amazon (mostly in plural Amazones) "one of a race of female warriors in Scythia," probably from an unknown non-Indo-European word, possibly from an Iranian compound *ha-maz-an- "(one) fighting together" [Watkins], but in folk etymology long derived from a- "without" + mazos "breasts," hence the story that the Amazons cut or burned off one breast so they could draw bowstrings more efficiently.

The river in South America (originally called by the Spanish Rio Santa Maria de la Mar Dulce) rechristened by Francisco de Orellana, 1541, after an encounter with female warriors of the Tapuyas (or, as some say, beardless, long-haired male tribesmen; still others hold that the name is a corruption of a native word in Tupi or Guarani meaning "wave").