[1] The coup is presumed to be named after the city of Bath in England and dates from the game of whist, the predecessor of bridge.
The basic position for the Bath coup is like this diagram: West leads the king at a notrump contract.
If the suit is divided 5–2, as in the diagram, the declarer has in effect performed a hold up with an additional gain in tempo, as the opponents have to regain the lead once each.
The defense can relatively easily prevent giving away the trick by free finesse by accurate signaling.
However, when a Bath coup position arises, defenders can't regain the tempo.