1590s, from Spanish El Dorado "the golden one," name given 16c. to the country or city believed to lie in the heart of the Amazon jungle, from past participle of dorar "to gild," from Latin deaurare, from de-, here probably intensive, + aurare "to gild," from aurum (see aureate). The story originated with the early Spanish explorers, and the place was sought for down to the 18th century.