One who in debauchery surpasses the rest of his companions, a blood or choice spirit. There are in London divers lodges or societies of Bucks, formed in imitation of the Free Masons: one was held at the Rose, in Monkwell-street, about the year 1705. The president is styled the Grand Buck. A buck sometimes signifies a cuckold.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Buck Bail * Buck’s FaceNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes