A secret plan or scheme made to prevent or oppose another secret plot or conspiracy.
From counter- + plot (a scheme or story). The word became popular in English during the 16th-17th centuries when tales of espionage and court intrigue flourished in literature and politics.
The Gunpowder Plot of 1605 was such a famous conspiracy that it created a whole cultural awareness of counterplots—spymasters and courtiers wrote books about the 'game' of plotting and counterplotting against each other.
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