Green’s Dictionary of Slang

1. the vagina; in pl., the labia.

c.1775		Only True and Exact Calendar [title page] A great many Common Hacks are in Town, to Run for small Plates, among whom are, Miss Jenny Whim, Molly May, Dianna Frost, Miss Handy, Dolly Thunderbum, Miss Sally Pouter.
1888–94		‘Walter’ My Secret Life (1966) V 942: Having a good look at the hairy pouters and notch. [Ibid.] IX 1844: Her cunt was a full sausage lipped pouter.
1896		Farmer Vocabula Amatoria (1966) 156: Haubert, m. The female pudendum; ‘the pouter’.

2. (Aus.) the male chest.

1919		W.H. Downing Digger Dialects 39: pouter — A man’s chest.
1924		(con. WWI) A.G. Pretty Gloss. Sl. [...] in the A.I.F. 1921–1924 (rev. t/s) n.p.: pouter. A Mans chest.