Green’s Dictionary of Slang

1. (US) a strong alcoholic drink.

1876		St Louis Globe-Democrat 19 Jan. n.p.: They nominate ‘bottled electricity,’ ‘lemonade with a stick in it,’ ‘jig-water,’ ‘budge,’ ‘bilge-water,’ ‘bug-juice,’ ‘rat-poison,’ ‘fusel-oil,’ ‘red-eye,’ ‘liquid ointment,’ ‘cut nails,’ ‘hard head,’ ‘benzine,’ ‘nitro-glycerine,’ ‘oil,’ ‘tea,’ ‘eye-water,’ ‘chain- lightning.’ [...] they all want the same article, alcohol, more or less diluted.
1954		J.D. MacDonald All These Condemned (2001) 29: Mavis came out of the bathroom [...] and took a fast knock at the Martini. ‘Go easy on that nitro, honey,’ I told her. ‘Last time you lost your sawdust.’.

2. (orig. US) nitroglycerine, as used in blowing open safes.

1903		St Louis Post-Dispatch 3 May II 2: Nito [sic] – Explosive to blow open a safe [HDAS].
1914		Wash. Post 11 Nov. Misc. 3/6: ‘Soup,’ ‘nitro’ and ‘dinny,’ all words which are self-explanatory.
1920		H.C. Witwer Kid Scanlon 235: Van Ness puts the gun and the nitro in Tony’s pocket.
1931		O. Von Gulker ‘Boomtown Album’ in Botkin Folk-Say 228: You have to be good to mix nitro – sulphuric acid, nitric acid, glycerin, and all the rest.
1944		C.B. Davis Rebellion of Leo McGuire (1953) 127: The first thing Idaho did was to put the nitro back in the medicine cabinet.
1959		‘Ed McBain’ Killer’s Wedge (1981) 25: Where the hell did she get a jar of nitro?
1969		‘Iceberg Slim’ Pimp 126: It was like a ton of nitro exploded inside me.
1976		P. Theroux Family Arsenal 74: A parcel of nitro in the tube station might do the trick, cause an earthquake in the Bakerloo cellar.
1987		G. Wolff ‘A Day at the Beach’ in A Day at the Beach (1992) 145: I popped a nitroglycerine tablet under my tongue, the time-honored remedy for victims of angina [...] the ‘nitro’ – as it’s known to its friends – was no remedy.
1992		G. Disher Paydirt [ebook] [W]e have to be prepared for good-old fashioned force—cutting gear, blasting with nitro or C4 plastic, whatever.
2023		(con. 1962) J. Ellroy Enchanters 371: Eddie brought owdered nitro. He knew how to rig controlled blow-outs.