dude

Uncertain, though likely a clipping of doodle (“fool, simpleton, mindless person”), perhaps with reference to the fashionable “Yankee Doodle dandy” in the 18th-century lyrics of the song “Yankee Doodle”; the word is first attested in 1883 as a New York City slang term of contempt for a “fastidious man, fop”. If so, then related to German Low German Dudeldop, Dudendop (“fool, dunce”), Saterland Frisian Duddigegen (“idiot”). It has also been suggested that the word is derived from dudes (“old rags”; compare duds) and dudesman (“scarecrow”), or possibly related to dawdle; It has also been suggested the word derives from the Irish dúid.

出典: Wiktionary「dude」（CC BY-SA 4.0）