A person who flatters or praises someone insincerely, especially behind their back.
From 'back' + 'fatter' (one who makes fat, from Old English 'fæt'). The term combines the idea of speaking behind someone's back with false praise.
This is an archaic insult that reveals how medieval and Renaissance people were just as concerned about two-faced behavior as we are today—the word shows human nature hasn't really changed.
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