Green’s Dictionary of Slang

1. for a man to withdraw the penis from the vagina; thus uncunting n.

1888–94		‘Walter’ My Secret Life (1966) I 92: Was this the first time I had ever been man enough to do it twice without uncunting? I think so.
1896		Farmer Vocabula Amatoria (1966) 91: Déconner. To withdraw after coition; ‘to decunt.’.
1902		G.R. Bacchus Confessions of Nemesis Hunt 1: He had me twice without uncunting as the vulgar put it; it was a paroxysm of gluttonous lust.

2. for a woman to remove the penis from the vagina.

1888–94

‘Walter’ My Secret Life (1966) I 79: A gay woman [...] gets the discharge near the outlet, uncunts you quickly, and at once washes and pisses at the same time.