To lie with a woman. The cull docked the dell all the darkmans; the fellow laid with the wench all night. Docked smack smooth; one who has suffered an amputation of his penis from a venereal complaint. He must go into dock; a sea phrase, signifying that the person spoken of must undergo a salivation. Docking is also a punishment inflicted by sailors on the prostitutes who have infected them with the venereal disease; it consists in cutting off all their clothes, petticoats, shift and all, close to their stays, and then turning them into the street.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Dobin Rig * DoctorNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes