Green’s Dictionary of Slang

classy adj.

of high or superior class, stylish, smart.

1884		Sporting Times 1 Nov. 3/5: Their get-up is usually of the classiest, and certainly they used to plank down their dibs.
1900		Marvel 15 May 13: Double event, too, so it must be classy, and I likes to be up-to-date.
1905–6		(?) H. Lawson ‘Triangles of Life’ in Roderick (1972) 644: [She] had the ingratiating smile, not for men, but for any woman, a rung above her in life — a little classier.
1911		G.R. Sims Off the Track in London 164: It was larger and more classy [...] than the dancing dram shops of Tiger’s Bay.
1913		Flint Daily Journal Jan.: Dat chorus is the classiest pack of dames dat kicked up their toes on the Bijou stage.
1922		Joyce Ulysses 721: And the land league sending me that long strool of a song out of the Huguenots to sing in French to be more classy O beau pays de la Touraine.
1925		Black Mask Aug. III 122: The usual environment of a ‘classy’ gambling house.
1936		J.T. Farrell World I Never Made 217: He must have dough to smoke fags as classy as these.
1940		M. Marples Public School Slang 4: Words expressing general approval [...] classy: characteristically an early twentieth-century word .
1946		Drake & Cayton Black Metropolis 499: Any entrepreneur who is trying to be particularly ‘classy’ feels a bevy of light girls desirable.
1952		Lait & Mortimer USA Confidential 94: You can usually find some of the classiest girls at the bar of the swank Darbury Room.
1959		W. Brown Teen-Age Mafia 20: She was a real classy dame.
1966		H.S. Thompson Hell’s Angels (1967) 99: Pete could really make a bike go [...] It was really classy the way he’d go out and win.
1969		F. Norman Norman’s London 206: The less classy whores of [...] Soho make do with simply putting a bell up outside their front doors.
1977		E. Bunker Animal Factory 85: It was a classy move, but futile.
1987		B. Chatwin Songlines 83: But a touch too classy for my little luncheon party!
1999		Guardian Guide 3–9 July 6: Tony takes his daughter on a tour of classy east coast universities.
2000		J. Baker Chinese Girl (2001) 148: A real classy piece lived here, no doubt about it.
2012		J. Fagan Panopticon (2013) 225: They do dominatrix stuff, high-class and kink only [...] It’s [i.e. a ‘dungeon’] a classy establishment.
2017		L. McInerney Blood Miracles : ‘She wasn’t impressed, no.’ ‘Ah. A classy bird so’.
2020		(con. 1991-94) W. Boyle City of Margins 36: Ludmilla’s classy. She probably dates rich guys who take her to steakhouses.

In compounds