A person who bluffs or deceives; a charlatan or fraud; someone who pretends to be something they're not.
From poker term 'four flush' (four cards of one suit, needing one more for a real flush), applied to people who fake or bluff; American slang from the late 1800s.
The term 'fourflusher' is a perfect linguistic fossil—it preserves the moment when poker players' slang invaded everyday English to describe any con artist!
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