Green’s Dictionary of Slang

1. to pry, to interfere, to listen in; thus snooping n. and adj.

1832		R.C. Sands Writings II 291: The world has realms wherein to snoop [DA].
1891		Journal of Amer. Folklore IV 160: Snoop.—This word I have frequently heard in New England, used both as a verb and as a noun. It implies sneaking, spying, prying around [DA].
1908		H. Green Maison De Shine 14: See to it that he kep’ where he b’longs. Men is all that snoopin’ that they’d oughta be licked. [Ibid.] 231: These fresh plain-clothes boys are snoopin’ around every place.
1917		‘A-No. 1’ From Coast to Coast with Jack London 114: Not even a snooping bluecoat was in sight.
1924		C.J. Dennis ‘The Crusaders’ in Chisholm (1951) 80: We’re moochin’ up the Lane, / Snoopin’ around for news we might obtain.
1937		E. Anderson Thieves Like Us (1999) 121: Old Filthy never did snoop around any more.
1947		S. Lewis Kingsblood Royal (2001) 13: She was plenty sore at our snooping.
1954		Oh Boy! No. 24 3: Little girls that snoop get into trouble!
1963		M. Spillane Return of the Hood 65: I’d take care of the guy my own way and he wouldn’t go snooping anywhere again.
1972		‘Hergé’ Tintin and the Land of Black Gold 7: If someone’s snooping, he’s had his chips!
1987		B. Chatwin Songlines 42: Aboriginals are sick and tired of being snooped at.
1997		H.S. Thompson Proud Highway 224: Thompson felt compelled to confess to snooping.
2007		T. Dorsey Hurricane Punch 20: You needed to lean on a twist, throw hopheads a yard, throw lead, no one snooped.
2015		Dly Chron. (De Kalb, IL) 7 July 12/1: My mother opens and reads my mail, snoops in my room and even smells my breath when I come home.

2. (also snoop over) to survey (surreptitiously).

1902		Ade Girl Proposition 32: The Young Fellow who simply keeps at the Girl and snoops around and plays House Dog until her Woman’s Heart is touched by his Slavish Devotion.
1915		Wall St Jrnl 9 July 10/1: Passing as American citizens [they] snoop and pry into the war secrets of another power.
1917		Wodehouse ‘Black For Luck’ Man with Two Left Feet 149: I seen him snooping about considerable time.
1924		D. Hammett ‘Night Shots’ Nightmare Town (2001) 87: After an hour of this snooping around, I returned to the house.
1939		R. Chandler Big Sleep 22: Private detectives [...] were greasy little men snooping round hotels.
1946		Mezzrow & Wolfe Really the Blues 68: She was doing a little snooping on her own.
1958		R. Prather Scrambled Yeggs 6: What you snooping around my place for?
1966		B. Reckord Skyvers I ii: This bloke caught snoopin’ y’see. E’s a spy and ’e knows what the price is.
1976		P. Theroux Family Arsenal 143: I caught her snooping, but she didn’t see nothing.
1989		C. Hiaasen Skin Tight 71: Reynaldo Flemm barely had time to snoop the joint over.
1990		S. Morgan Homeboy 209: What the fuck you doin snoopin around that car?
2000		N. Griffiths Grits 26: If they rirly gave Annie’s story any credence [...] they woulduv just snooped on me straightaway an obtained proof.
2013		T. Dorsey Riptide Ultra-Glide 98: Then the cops started snooping around.

3. to steal.

1924		Galsworthy White Monkey 59: Look here, Bicket, if we let you snoop copies, all the packers will snoop copies.
1961		‘Frank Richards’ Billy Bunter at Butlins 207: He won’t snoop your jolly old wallet this time, old fat man.