Green’s Dictionary of Slang

1. (also gumfoot) to investigate, esp. used of police officers or private detectives; thus gumshoeing as n.

1908		B. Fisher A. Mutt in Blackbeard Compilation (1977) 135: It is true I had Rudolph Tobasco gumshoeing for my lost quadruped.
1911		S. Ford Torchy 12: This duck from the post-office buildin’ showed up. He comes gumshoein’ around one noon hour [...] and he asks a whole lot of questions.
1922		Washington Times (DC) 12 Nov. n.p.: I let him get away with it until I can gumshoe around a bit.
1925		D. Hammett ‘Dead Yellow Women’ Story Omnibus (1966) 154: I had once, half-joking, promised to give the lad a fling at gum-shoeing.
1933		R. Chandler ‘Blackmailers Don’t Shoot’ in Red Wind (1946) 119: It was his night off and he was a great guy to gumshoe around on his night off.
1949		Monteleone Criminal Sl. (rev. edn) 108: gumfoot [...] to spy for the police.
1955		B. Schulberg On the Waterfront (1964) 116: How do you like them two gumshoein’ around, takin’ me for a pigeon.
1962		Ragen & Finston World’s Toughest Prison 802: gumshoe – To spy on or to observe.
1977		‘John le Carré’ Honourable Schoolboy 77: Gum-shoeing after Commercial Boris.
2002		B. Pratt Idea of Forever 53: I’m going to send Pablo out immediately to start gumshoeing and he’ll probably begin night here.

2. to walk softly, to creep around; thus gumshoeing as n. and adj.

1902		‘Hugh McHugh’ It’s Up to You 15: I left Tacks on guard and gumshoes away like Raffles, the busy burglar.
1912		G.R. Chester Five Thousand an Hour Ch. xxiii: Has that grasping old monopolist gumshoed into town again?
1922		Colton & Randolph Rain II 101: He wasn’t looking any too well when I saw him gumshoeing down the road this morning.
1937		P. Cheyney Dames Don’t Care (1960) 122: I leave him, open the door an’ start gumshoein’ up the stone steps.
1943		R.L. Bellem ‘Shakedown Sham’ Dan Turner – Hollywood Detective May 🌐 I gumshoed over to the connecting door between my quarters and the adjoining 607. I put my ear to the panel; listened.
1949		J.H. Burns Lucifer with a Book 43: He is the camouflaged forceps of Mr. Pilkey’s Puritanism, of his gumshoeing cynosure.
1954		A. Petry Narrows 247: She and Link walk gumshoe when dey come in [...] Dey gumshoe in, through door.
1998		W.J. Schafer Mapping the Godzone 156: Ever since he got dubbed ‘the Spook’ at school he’s never happy unless he’s gumshoeing around in the dark.

3. to walk, to stroll; to travel.

1889		News-Herald (Hillsboro, OH) 12 Dec. 1/4: Geo. W. Hall [...] is gum-shoeing it over the State for Brice.
1915		S. Ford Shorty McCabe on the Job 139: Is it the style where you come from [...] to gumshoe around and peek in the windows to see old friends?
1942		R.L. Bellem ‘Daughter of Murder’ Dan Turner – Hollywood Detective Dec. 🌐 On the third floor corridor I gumshoed toward my portal.
1955		B. Appel Tough Guy [ebook] [A] federal who’d gumshoed the backroads upstate and uncovered the new route being used by Big Bill Dwyer’s gang.
2004		Nystrom & Konn Lonely Planet Bolivia 56: You’ll get plenty of exercise gumshoeing up and down the Prado.

4. to be quiet.

1913

‘Lord Ballyrot in Slangland’ in Tacoma Times (WA) 23 July 4/4: Nix on the patriotic and ragtime selections every time you did a shovel full of canned broth into your map. Gum-shoe, kid, gum-shoe.

5. (US teen) to search out amorous couples in parked cars in order to surprise them by shining a light on them.

1949–51

in M. Daly Profile of Youth 233: Even when fellows are out stag, a car is indispensable to ‘gumshoeing,’ the practice of driving to a favorite necking spot and beaming a flash or spotlight into parked cars.