Green’s Dictionary of Slang

1. the throat.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue n.p.: gutter lane the throat, the swallow, the red lane.
1811		Lex. Balatronicum.
1835		G. Kent Modern Flash Dict.
1841		Punch i 169: Men with swallows like Thames Tunnels.
1850		Manchester Spy (NH) 2 Nov. n.p.: ‘Shut your eyes, open your swallow wide and keep a stiff upper lip’’.
1912		Bulletin (Sydney) 10 Oct. 48/2: Presen’ly bits o’ th’ beers will grease ’is swaller all th’ way down, an’ he’ll come in fa th’ fourth beer.

2. a mouthful.

1821		W.T. Moncrieff Tom and Jerry III iii: There’s a swallow, Herry, this fellow is a perfect mop.
1840		Southern Sketches 33: Then he took out a tickler of whiskey; and, after he’d took three or four swallows out ’n it, says he, ‘Oblige me by taking a horn’ [F&H].
1885		A.H. Buck Hbk of Medical Sciences v 4: A swallow or two of hot milk sometimes aids in coughing up tenacious mucus [F&H].
1898		E.N. Westcott David Harum 212: She took a swallow of the wine.
1927		H.C. Witwer Classics in Sl. 53: Bein’ that close to her sent my blood crashin’ through my veins like I hadst just quaffed off a swallow of this prohibition hooch!
1943		C. McCullers Heart is a Lonely Hunter (1986) 156: As she ate she drank a glass of water to help wash down the swallows.

3. (US) an alcoholic drink.

1877

Sporting Gaz. (London) 9 June 541/3: I [...] asked her to waltz ;her answer, with its indescribable nasal twang and its latest Yankee slang for a liquor, is still ringing in my ears—‘With pleasure,’ she said, ‘but I must have a swallow first, I guess’.

4. a puff of a cigarette.

1984

Partridge DSUE (8th edn) 1181/1: C.20.

5. (N.Z. prison) an informer.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 182/1: swallow n. an informer, a nark.