Green’s Dictionary of Slang

first-rate, excellent; usu. referring to the quality of a drug; also as excl. (see cite 2010).

1897		Mirror of Life 9 June 3/1: [W]e thought the bold Barney Scannell, whose French is quite equal to his Irish, was primo in boxing affairs across the ‘silver streak’.
1970		Atlantic Monthly Jan. 10/2: Who’s buying the primo stuff [i.e. marijuana]? None of my people can touch it – it goes for $120 to $200 an ounce.
1981		J. Ellroy Brown’s Requiem 44: The courses round here are the primo land in L.A., worth billions of bucks.
1992		M. Leyner Et Tu, Babe (1993) 76: Sure the lincoln’s morning breath had been primo shit.
1993		R. Shell Iced 136: Dalek [...] pulled out a pouch of some primo-reefer.
1995		G.A. Haywood ‘And Pray Nobody Sees You’ in Woods Spooks, Spies and Private Eyes (1996) 185: Orange ’65 Mustang in primo condition.
1999		D. Looser ‘Boob Jargon’ in NZEJ 13 34: primo adj. Good, excellent.
2004		E. Weiner Drop Dead, My Lovely (2005) 45: I’m whack on contracts but do primo litigation.
2004		L. Redhead Peepshow [ebook] Primo shit [i.e. cocaine]. You can’t get this on the street.
2009		T. Black Gutted 253: I pointed the way through the winding streets, littered with deros, trash and more than a few needles [...] ‘No exactly primo real estate’.
2010		L. Berney Gutshot Straight [ebook] ‘Primo!’ Rock Star said, bouncing around with delight and relief.
2017		D. Winslow The Force [ebook] It’s primo shit [...] A sweet, mellow high.
2020		T. Pluck ‘Hula Hula Boys’ in What Pluckery Is This? (28 Jan 2024) 🌐 Hani’s primo weed was enough to make her strip out of her bikini to moon-bathe.