A man in the civil line, a townsman, or tradesman: a military term, from the mohair buttons worn by persons of those descriptions, or any others not in the army, the buttons of military men being always of metal: this is generally used as a term of contempt, meaning a bourgeois, tradesman, or mechanic.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Mobility * MoietyNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes