Green’s Dictionary of Slang

1. (US) bright, lively, exciting.

1917		Variety 30 Nov. 19: A dance number of the jazzy syncopated type.
1923		H.C. Witwer Fighting Blood 76: So the three of us does some close harmony on ‘Silver Threads Amongst the Gold,’ [...] winding up with something good and jazzy.
1939		R. Chandler Big Sleep 124: She’d make a jazzy week-end, but she’d be wearing for a steady diet.
1943		M. Harrison Reported Safe Arrival 9: He wore a blue jumper of that inarticulate boisterousness called ‘jazzy’.
1955		E. Hunter Blackboard Jungle 166: This was going to be real jazzy.
1961		(con. 1945) G. Forbes Goodbye to Some (1963) 273: You see those murals? Are they jazzy or not?
1963		R.L. Finn Time Remembered (1985) 125: The Lane on Sundays, the blaring jazzy lane.
1998		(con. 1986) G. Pelecanos Sweet Forever 73: Lookin’ for somethin’ jazzy and fine.
2000		Indep. on Sun. Real Life 23 Jan. 3: There’s no [...] jazzy explosion of clashing hues.

2. (US) ostentatious, brash.

1920		Wash. Times (DC) 30 May 31/1: Jazzy ways of wearing your jewels.
1923		letter 8 Nov. in P. Jay Sel. Correspondence of Burke and Cowley (1990) 147: I wrote a jazz poem in jazzy prose.
1938		R. Chandler ‘The King in Yellow’ in Spanish Blood (1946) 69: Your clothes should be very jazzy. Very jazzy indeed, Steve.
1949		‘Hal Ellson’ Duke 71: He had a big jazzy car.
1958		T. Capote Breakfast at Tiffany’s 76: I’ve always thrown out such a jazzy line.
1969		‘Iceberg Slim’ Mama Black Widow 79: I recognized the huge black guy [...] as a flunkey for the jazzy minister.
1974		D. Goines Never Die Alone 14: The bastard won’t be so jazzy when [...] the boys finish with his ass.
1992		D. Pinckney High Cotton (1993) 81: A jazzy woman, my mother called her, a divorcée, sold us the house.
2008		Sun. Times (S.Afr.) 27 Jan. 21: She too sported a jazzy Afro.
2019		N. Walker Cherry 23: [of tennis shoes] ‘All white. And none of the jazzy designs on them either’.