The Collaborative International Dictionary of English v.0.48:

Punish \Pun"ish\, v. t. [imp. & p. p. Punished; p. pr. & vb.
   n. Punishing.] [OE. punischen, F. punir, from L. punire,
   punitum, akin to poena punishment, penalty. See Pain, and
   -ish.]
   1. To impose a penalty upon; to afflict with pain, loss, or
      suffering for a crime or fault, either with or without a
      view to the offender's amendment; to cause to suffer in
      retribution; to chasten; as, to punish traitors with
      death; a father punishes his child for willful
      disobedience.
      [1913 Webster]

            A greater power
            Now ruled him, punished in the shape he sinned.
                                                  --Milton.
      [1913 Webster]

   2. To inflict a penalty for (an offense) upon the offender;
      to repay, as a fault, crime, etc., with pain or loss; as,
      to punish murder or treason with death.
      [1913 Webster]

   3. To injure, as by beating; to pommel. [Low]
      [1913 Webster]

   4. To deal with roughly or harshly; -- chiefly used with
      regard to a contest; as, our troops punished the enemy.
      [Colloq. or Slang]
      [Webster 1913 Suppl.]

   Syn: To chastise; castigate; scourge; whip; lash; correct;
        discipline. See Chasten.
        [1913 Webster]

WordNet (r) 3.0 (2006):

punish
    v 1: impose a penalty on; inflict punishment on; "The students
         were penalized for showing up late for class"; "we had to
         punish the dog for soiling the floor again" [syn: punish,
         penalize, penalise]

Moby Thesaurus II by Grady Ward, 1.0:

101 Moby Thesaurus words for "punish":
   abuse, admonish, agonize, amerce, avenge, banish, batter, be quits,
   beat, beat up, birch, bloody, bring to account, bring to book,
   call to account, cane, cashier, castigate, chasten, chastise, claw,
   convulse, correct, criticize, crucify, damage, deal with,
   discipline, draw and quarter, dress down, electrocute,
   even the score, excommunicate, excruciate, execute, exile, fine,
   fix, flog, get even with, handicap, hang, harm, harrow, hurt,
   impale, imprison, incarcerate, inflict upon, injure,
   kill by inches, knock about, knock around, lacerate, lambaste,
   lancinate, lash, lock up, macerate, make quits, maltreat,
   manhandle, martyr, martyrize, masthead, maul, mulct, paddle,
   penalize, pillory, polish off, put away, put down, rack, rebuke,
   reprove, revenge, rip, rough up, savage, scarify, scold, scourge,
   send down, send up, settle the score, settle with, shift, spank,
   square accounts, swill, take revenge, take to task,
   tar and feather, thrash, torment, torture, trounce, visit upon,
   whip, wring