Green’s Dictionary of Slang

1. (also dudy) showy, smart.

1888		A. Trumble Mott Street Poker Club 43: No vestige of the dude suit was visible about him. He wore the conventional blue blouse.
1895		E. Townsend Chimmie Fadden Explains 8: He taut I’d be so dudy de Duchess wouldn’t know me.
1897		E.W. Townsend Chimmie Fadden 35: Well, I had me buttons off, and was rigged up in me new dude harness.
1905		G.W. Peck Peck’s Bad Boy Abroad 20: I ain’t running a dude place.
1915		Wodehouse Psmith Journalist (1993) 209: He’s wearin’ a dude suit an’ shiny shoes.
1920		F. Packard White Moll 88: You’ve been getting wise to a whole lot lately, you and that dude pal of yours.
1930		A. Carey Memoirs of a Murder Man 12: ‘This,’ said Kelso, according to the legend, ‘is the crime of a gentleman,’ and he pointed to the imprint. ‘Long, thin, ladylike fingers. A dude killer.’.
1944		N. Pepper in Baltimore Sun (MD) 20 Feb. A2/2: That’s Really Dude — That’s sharp.
1946		(con. 1910s) J. Thompson Heed the Thunder (1994) 27: Even ol’ Dude Grant looked ready to fight at the drop of a hat today.
1972		D. Jenkins Semi-Tough 89: He’s handsome, a dude dresser, and has the gift of bullshit.
1987		(con. 1920s) L. Redmond Emerald Square 43: Bang-Bang had bailed up a dude gambler from Rathgar.
1999		Guardian Guide 19–25 June 3: Ladies dress up in dude duds.

2. a general term of approbation.

1895		E. Townsend Chimmie Fadden Explains 82: We [...] went t’ de candy shop and de flower store for some dude tings Mr. Paul wanted for Miss Fannie.
1987		‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 33: One great mob kung-fu fight with some dude kickers in a corral.

3. of one who is posing as a cowboy.

1922		Wkly Jrnl Miner (Prescott, AZ) 5 July 3/4: The next couple was from the dude hotel at Castle Hot.
1933		Buckner ‘Ranch Diction of the Texas Panhandle’ in AS VIII:1 26: They are not trumped up to embellish a short story written by some man who never saw a horse or cow except perhaps on a dude ranch.
1934		O. Strange Sudden 8: Dude puncher, tryin’ to put up a two-gun bluff.
1937		P. Cheyney Dames Don’t Care (1960) 32: Two or three cowboys — real or dude I don’t know.
1937		‘F. Bonnamy’ Death on a Dude Ranch (1953) 34: Luke, the dude wrangler [...] dressed exactly as a cowboy is expected to dress.
1941		J.M. Cain Mildred Pierce (1985) 504: That’s a dude ranch near Winslow, Arizona.
1971		B. Moyers Listening to America 144: Is that Chet Huntley barking instructions to a construction gang putting up a dude ranch?