Leathern cases of stiff leather, used in Devonshire instead of boots; they are fastened to the saddle, and admit the leg, shoe and all: the name was at first jocularly given.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Gambs * GamblerNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes