A cheat, or trick. To cut a sham; to cheat or deceive. Shams; false sleeves to put on over a dirty shirt, or false sleeves with ruffles to put over a plain one. To sham Abram; to counterfeit sickness.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
See also the definition in Nathan Bailey's 1736 dictionary of canting and thieving slang.
Shallow * To ShambleNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes