Green’s Dictionary of Slang

monosyllable n.

the vagina.

1680		School of Venus 107: Whic word Cunt is very short and fit [...] methinks indeed they do ill, that make such a pather, to describe a Monosyllable by new words and longer ways.
1709		Virgin Unmask’d 49: All this occasioned by some silly naughty word [...] perhaps a bawdy Monsyllable, such as boys write upon walls.
1714		T. Lucas Lives of the Gamesters (1930) 216: Some silly naughty word [...] perhaps a baudy monosyllable, such as boys write upon walls.
1786		Pinkerton Ancient Scot. Poems 384: Addison [...] thought nothing [...] to tell us that a monosyllable was his delight [F&H].
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: Venerable Monosyllable. **** or Pudendum Mulibre.
c.1786		Grose Classical Dict. of the Vulgar Tongue ms. additions n.p.: The Monosyllable. ++++. A woman’s commodity.
1793		Bacchanalian Mag. 41: Of a fam’d Monosyllable, doubtless, you’ve heard, / That whenever ’tis ripe, is set off by a beard.
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn) n.p.: Monosyllable. A woman’s commodity. [Ibid.] Venerable Monosyllable. Pudendum muliebre.
1811		Lex. Balatronicum [as cit. 1796].
1819		Byron in letter to Douglas Kinnaird 26 Oct. I have such projects for the Don — but the Cant is so much stronger than the Cunt — now a days, — that the benefit of experience in a man who had well weighed the worth of both monosyllables — must be lost to despairing posterity.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 120: Monosyllable — (the); feminine only and described by Nat Bailey as pudenda mulieris. Of all the thousand monosyllables in our language this one only is designated by the definite article — the monosyllable; therefore do some men call it ‘the article,’ ‘my article,’ and ‘her article,’ as the case may be.
1836		‘Toasts’ in Gentleman’s Private Songster in Spedding & Watt (eds) Bawdy Songbooks (2011) III 383: The monosyllable in the middle of a good subject.
1838		Crim.-Con. Gaz. 1 Dec. 120/1: What in one single syllable better express’d? / That syllable, then, I my sentiment call? / So here’s to that word which is one word for all.
1890–1904		Farmer & Henley Sl. and Its Analogues.