Geronimo

wiktionary

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Various theories; see Wikipedia.

etymonline

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Geronimo (interj.)

cry made in jumping, 1944 among U.S. airborne soldiers, apparently from the story of the Apache leader Geronimo making a daring leap to escape U.S. cavalry pursuers at Medicine Bluffs, Oklahoma (and supposedly shouting his name in defiance as he did). Adopted as battle cry by paratroopers in World War II, who perhaps had seen it in the 1939 Paramount Studios movie "Geronimo." The name is the Italian and Spanish form of Jerome, from Greek Hieronomos, literally "sacred name." One contemporary source also lists Osceola as a jumping cry.