country name, from Persian Iran, from Middle Persian Ērān "(land) of the Iranians," genitive plural of ēr- "an Iranian," from Old Iranian *arya- (Old Persian ariya-, Avestan airya-) "Iranian", from Indo-Iranian *arya- or *ārya-, a self-designation, perhaps meaning "compatriot" (see Aryan).
In English it began to be used 1760s, by orientalists and linguists (Alexander Dow, William Jones), in historical contexts, and usually with a footnote identifying it with modern Persia; as recently as 1903 "Century Dictionary" defined it as "the ancient name of the region lying between Kurdistan and India." In 1935 the government of Reza Shah Pahlavi requested governments with which it had diplomatic relations to call his country Iran, after the indigenous name, rather than the Greek-derived Persia.