"philanderer," from the legendary dissolute Spanish nobleman whose rakish exploits formed the stuff of popular tales in Spain from early 17c., dramatized by Gabriel Tellez in "Convivado de Piedra." Adapted into French and Italian before 1700; Used attributively in English for "ladies' man, womanizer" from the time of Byron's popular poem about him (1819).[don juan etymology, don juan origin, 英语词源]