Green’s Dictionary of Slang

leak n.

1. the female genitals.

J. Gay ‘Work for a Cooper’ in Poetical Works of John Gay (1854) 213: Her coats rose high, her master saw – I see – he cries – (then claspt her fast) The leak through which my wine has past .
[UK] ‘Witcomb Bay’ in Cockchafer 12: He press’d her downy billow, / And soon he stopp’d her leak.

2. (orig. US) the act of urination.

implied in take a leak
[US]Kerouac On the Road (The Orig. Scroll) (2007) 180: I drank so much I had to rush out of the booth for a leak every two minutes.
[Aus]W. Dick Bunch of Ratbags 148: He’s just gone for a leak.
[Can]R. Caron Go-Boy! 107: Hang on just a minute, will you? I gotta have a leak.
[UK]F. Taylor Auf Wiedersehen Pet Two 37: He’d not even dared to stop for a leak until he’d hit the A1.
[Aus]C. Bowles G’DAY 5: When an Australian goes to urinate [...] he most often goes for a piss, a slash, or a leak. He hardly ever shakes hands with the wife’s best friend.
[Aus]T. Winton ‘Big World’ in Turning (2005) 6: We pull over for a leak.

3. (orig. US) a piece of hitherto secret information that has been revealed.

[Perrysburg Jrnl 1 Sept. 6/1: For some time now a constant ‘leakage’ of these confidential documents had been noticed [...] and Dreyfus was under suspicion.
R.H. Davis Frame Up 🌐 n.p.: Both your brother and Sammy [...] asked you wouldn’t use the telephone; they’re afraid of a leak.
[US]Wood & Goddard Dict. Amer. Sl.
[US]E.H. Lavine Third Degree (1931) 68: After the arrest the gang figured there must be a leak from the outside.
[UK]G. Fairlie Capt. Bulldog Drummond 185: The knowledge which he had acquired [...] might be the means effectively of stopping a very dangerous leak.
[US]M. Spillane One Lonely Night 100: The leak could just as well have come out of police headquarters.
[US]C. Cooper Jr Scene (1996) 146: I’ll string out a few feelers for leaks.
[UK]Guardian Media 19 July 2: A series of leaks described him as a management naif.
(con. 1932-3) D. Frith Bodyline Autopsy 189: [Jack] Fingleton’s claim that it was [Don] Bradman who was responsible for steering the leak for public consumption.
[Scot]V. McDermid Out of Bounds (2017) 81: There’s a leak somewhere in my ystrem. The media gets to hear about the cases .

4. (Aus., also leaker) an informer.

[US]F. Packard White Moll 142: Where did you get the dope you made your plays with? It was a cinch, wasn’t it, that there was a leak somewhere in our crowd.
[US]W.R. Burnett Quick Brown Fox 230: [T]here was a leak in the News-Press, and Kelly got tipped off to anything big that was coming up, just in case he missed it himself.
[US] in Woodward & Bernstein The Final Days 319: Haig had a low opinion of Hartmann [...] whom he judged a heavy drinker and a leaker.

5. (Aus.) a trick, a dodge.

[Aus]A. Marshall These Are My People (1957) 144: I use Eno’s Fruit Salts instead of baking powder [...] I know all the leaks.

In phrases

put the leak(e) into (v.)

(US) to trick, to deceive.

[US]T. Haliburton Clockmaker II 89: You’ve put the leake into ’em this hitch rael complete; it’s grand!
[US]T. Haliburton Sam Slick in England II 127: He can’t put the leake into me that way.
[US]T. Haliburton Nature and Human Nature I 237: I have done it myself [...] puttin’ the leak into a consaited critter sometimes for fun.
take a leak (v.) (also spring a leak)

1. to have a venereal disease.

[UK]Fletcher Chances II ii: anthony: Thou hast such a Master for that chase, That till he spend his maine Mast—— peter: Pray remember Your courtesie good Anthony; and withall, How long ’tis your Master sprung a leak, He had a sound one since he came.

2. (also hang a leak) to urinate.

‘Mlle. from Armentieres’ 🎵 The proper place to take a leak / Is right on the corner of the main street.
[US]J.T. Farrell Gas-House McGinty 188: You got so much slob around that gut you ain’t seen yourself take a leak for years.
[UK]‘Henry Green’ Caught (2001) 43: The man looked at him expressionless, said no word, unbuttoned his trousers and [...] sprang a leak on to the pavement.
[US](con. 1944) N. Mailer Naked and Dead 183: If you have to take a leak, for God’s sake go outside.
[US]Monteleone Criminal Sl. (rev. edn) 221: spring a leak [...] to urinate.
[US]C. Himes Crazy Kill 141: You sure it wasn’t just to take a leak.
[US]N. Heard Howard Street 70: I gotta take a leak. Be right back.
[US]L.K. Truscott IV Dress Gray (1979) 174: You might have to take a leak, the call of nature.
[UK]T. Paulin ‘Local Histories’ in Liberty Tree 44: He leaves his russet hide to take a leak.
[US]R. Price Clockers 4: If he was to go take a leak, the guy would be lying in the grass with a crease in his hat.
[US](con. 1970s) G. Pelecanos King Suckerman (1998) 19: [They] could check out your equipment while you were trying to take a leak.
[US]T. Dorsey Florida Roadkill 177: Marla Maples took a leak in the beach right there.
[US]C. Hiaasen Skinny Dip 112: She let her damn mutts take a leak on my tar!
[Aus]L. Redhead Peepshow [ebook] He stopped at a palm tree to hang a leak [...] but only a thin trickle of urine dribbled out.
[Aus]L. Redhead Thrill City [ebook] He never hangs a leak, despite sinking copious quiantities of Coppers Pale.
[US]J. Stahl Happy Mutant Baby Pills 99: The guy who jumps out of a building and pancakes another guy taking a leak when he lands.