to harass (somebody) in a manner designed to injure or afflict them, esp because of their race, religion, political beliefs, etc
to annoy (somebody) with persistent or urgent approaches, attacks, pleas, etc
persecution /-ʹkyoohsh(ə)n/ noun
persecutive /-tiv/ adj
persecutor noun
persecutory /-ʹkyooht(ə)ri/ adj
[early French persecuter, back-formation from persecuteur persecutor, from late Latin persecutor, from Latin persequi to pursue, persecute, from per- + sequi to follow]