Green’s Dictionary of Slang

covered way n.

the vagina.

1751		Smollett Peregrine Pickle (1964) 641: Their chief [...] returned the salute, by observing, that there was no occasion for an horn-work, when the covered way was not worth defending.
1768		Gentleman’s Bottle-Companion 8: The siege began, unmask’d she lay, / He quickly gain’d the cover’d way.
1787		Harris’s List of Covent-Garden Ladies 75: [She] does not refuse any visitant who able to cover his approaches to her covered work with one pound note.
1788		‘The Gobbio’ Chap Book Songs 7: And soon he got on the cover’d way, / He battered a breach, but missed his reach.
1790		‘Bumper Allnight. Esquire’ Honest Fellow 8: For none but dear Shandy she said, / Shou’d dance upon her cover’d way.
1890–1904		Farmer & Henley Sl. and Its Analogues.
1896		Farmer Vocabula Amatoria (1966) 194: Navire, n. The female pudendum; ‘the covered way’.