A person who deceives or speaks nonsense; a deceiver or charlatan using gammon (false talk).
From gammon (to deceive) plus the agent suffix -er, denoting someone who habitually performs the action of deceiving.
A gammoner was basically a con artist or smooth talker—the word vanished from English but captured a type of person who's always existed: the charmer who sells you what you don't need with a smile.
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