A cheat: probably from the thievish disposition of the birds of that name. Also the cant name for a crow used in house-breaking. To rook; to cheat, particularly at play.
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.
Romp * RoomNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes