She prays with her knees upwards; said of a woman much given to gallantry and intrigue. At her last prayers; saying of an old maid.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Prattling Box * Preadamite QuacabitesNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes