To go off with the fall of the leaf; to be hanged: criminals in Dublin being turned off from the outside of the prison by the falling of a board, propped up, and moving on a hinge, like the leaf of a table. IRISH TERM.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Lazybones * To LeakNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes