Green’s Dictionary of Slang

1. a widow.

1773		O. Goldsmith She Stoops to Conquer Act III: There’s Mrs. Mantrap, Lady Betty Blackleg, the countess of Sligo, Mrs. Langhorns, old Miss Biddy Buckskin.
1859		Matsell Vocabulum.
1882		Dly Dispatch (Richmond, VA) 1 Nov. 3/3: ‘Man-trap’ [...] a widow’.
1895		C. Crowe Aus. Sl. Dict. 48: Man Trap, a widow.
1901		Argus (Melbourne) 20 Sept. 6/4: A widow is known to him as a [...] mantrap or an ace of spades, while an old maid is generally a quail.

2. the vagina.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: Mantrap, a woman’s commodity.
1811		Lex. Balatronicum [as cit. 1785].
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue [as cit. 1785].
1888–94		‘Walter’ My Secret Life (1966) VII 1350: We got into bed again, and I looked at their carnal man traps.
1890–1904		Farmer & Henley Sl. and Its Analogues.

3. (UK Und.) the gallows.

c.1790

‘De Kilmainham Minit’ in Luke Caffrey’s Gost 6: When we came to de Man-trap, and saw, / Poor Luke look so blue in de Gabbard.

4. (US) a brothel.

1856

Life in Boston & N.Y. (Boston, MA) 11 Oct. n.p.: Mrs Worcester, who formerly kept a man-trap at the West End, has removed to harrison Avenue.

5. (Aus.) a public house.

1885

Bulletin (Sydney) 29 Aug. 5/1: While talking to a man in a well-known man-trap, his mate came behind me and set fire to my Crys, at the same time telling me to go to —.

6. an attractive and available woman.

1784		Rambler’s Mag. May 181/1: Damned fine girls here, Mr Benedict, eyeing the numerous man-traps, that momently passed and repassed the window [...] I believe the attraction is usually about the centre.
1951		G. Marx letter 15 Nov. in Groucho Letters (1967) 157: Steer clear of these man-traps. Marry, if you must, but don’t marry a chorus girl.