To conger; the agreement of a set or knot of booksellers of London, that whosoever of them shall buy a good copy, the rest shall take off such a particular number, in quires, at a stated price; also booksellers joining to buy either a considerable or dangerous copy.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Confect * CongoNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes