The Collaborative International Dictionary of English v.0.48:

Persecute \Per"se*cute\, v. t. [imp. & p. p. Persecuted; p.
   pr. & vb. n. Persecuting.] [F. pers['e]cueter, L. persequi,
   persecutus, to pursue, prosecute; per + sequi to follow,
   pursue. See Per-, and Second.]
   1. To pursue in a manner to injure, grieve, or afflict; to
      beset with cruelty or malignity; to harass; especially, to
      afflict, harass, punish, or put to death, for adherence to
      a particular religious creed or mode of worship.
      [1913 Webster]

            Do good to them that hate you, and pray for them
            which despitefully use you, and persecute you.
                                                  --Matt. v. 44.
      [1913 Webster]

   2. To harass with importunity; to pursue with persistent
      solicitations; to annoy. --Johnson.
      [1913 Webster]

   Syn: To oppress; harass; distress; worry; annoy.
        [1913 Webster]

WordNet (r) 3.0 (2006):

persecute
    v 1: cause to suffer; "Jews were persecuted in the former Soviet
         Union" [syn: persecute, oppress]

Moby Thesaurus II by Grady Ward, 1.0:

123 Moby Thesaurus words for "persecute":
   abuse, afflict, aggravate, aggrieve, annoy, badger, bait, be at,
   bedevil, befoul, beset, bewitch, blight, bother, bristle,
   brown off, bug, bully, bullyrag, burn up, chivy, condemn, corrupt,
   crucify, curse, damage, defile, deprave, despoil, destroy, devil,
   disadvantage, discompose, disserve, distemper, distress, disturb,
   do a mischief, do evil, do ill, do wrong, do wrong by, dog, doom,
   dragoon, envenom, exasperate, exercise, fash, fret, get,
   get into trouble, gripe, harass, harm, harry, haunt, heckle,
   hector, hex, hound, hunt, hurt, ill-treat, impair, importune,
   infect, injure, irk, irritate, jinx, maltreat, martyr, menace,
   miff, mistreat, molest, nag, needle, nettle, nudzh, oppress,
   outrage, peeve, pester, pick on, pique, plague, play havoc with,
   play hob with, pluck the beard, poison, pollute, pother, prejudice,
   provoke, punish, pursue, rack, ride, rile, roil, ruffle, savage,
   scathe, subjugate, suppress, taint, tease, threaten, torment,
   torture, trouble, try the patience, tweak the nose, tyrannize, vex,
   victimize, violate, worry, wound, wreak havoc on, wrong