Before revision: From this, it became a slang word for the secret and equally incomprehensible mutterings of a cant language used by beggars, thieves, gypsies , etc., and then the fluent plausible talk that a cheap-jack employs to pass off his goods.
After revision: From this, it became a slang word for the secret and equally incomprehensible mutterings of a cant language used by beggars, thieves, fences , etc., and then the fluent plausible talk that a cheap-jack employs to pass off his goods.