A person who lives by passing base coin. The cove was fined in the steel for smashing; the fellow was ordered to be imprisoned in the house of correction for uttering base coin.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Smart Money * SmashNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes