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early 15c., from Anglo-French persecutour, Old French persecutor "persecutor, enemy" (12c., Modern French persécuteur), from Latin persecutor, agent noun from persequi (see persecution).
mid-15c., "to oppress for the holding of a belief or opinion," from Middle French persécuter "pursue, torment, open legal action" (14c.), from Latin persecutus, past participle of persequi "to pursue" (see persecution). Related: Persecuted; persecuting.