The Collaborative International Dictionary of English v.0.48:

Wickedness \Wick"ed*ness\, n.
   1. The quality or state of being wicked; departure from the
      rules of the divine or the moral law; evil disposition or
      practices; immorality; depravity; sinfulness.
      [1913 Webster]

            God saw that the wickedness of man was great. --Gen.
                                                  vi. 5.
      [1913 Webster]

            Their inward part is very wickedness. --Ps. v. 9.
      [1913 Webster]

   2. A wicked thing or act; crime; sin; iniquity.
      [1913 Webster]

            I'll never care what wickedness I do,
            If this man comes to good.            --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

wickedness
    n 1: morally objectionable behavior [syn: evil, immorality,
         wickedness, iniquity]
    2: absence of moral or spiritual values; "the powers of
       darkness" [syn: iniquity, wickedness, darkness, dark]
    3: the quality of being wicked [syn: nefariousness,
       wickedness, vileness, ugliness]
    4: estrangement from god [syn: sin, sinfulness,
       wickedness]
    5: the quality of being disgusting to the senses or emotions;
       "the vileness of his language surprised us" [syn:
       loathsomeness, repulsiveness, sliminess, vileness,
       lousiness, wickedness]

Moby Thesaurus II by Grady Ward, 1.0:

94 Moby Thesaurus words for "wickedness":
   aberrance, aberrancy, abnormality, arrantness, badness, baseness,
   bitchiness, corruption, criminality, cussedness, damnability, debt,
   delinquency, depravity, deviance, deviancy, devilishness,
   devilment, devilry, deviltry, evil intent, evilness, fiendishness,
   flagitiousness, foulness, godlessness, harmfulness, hatefulness,
   heinousness, hellishness, illegality, immorality, impiety,
   improperness, impropriety, inaccuracy, inappropriateness,
   inauspiciousness, incorrectness, indecorousness, indecorum,
   inexpedience, inferiority, infraction, iniquitousness, invalidity,
   invidiousness, irreligion, maleficence, malevolence, malice,
   malice aforethought, malice prepense, maliciousness, malignance,
   malignancy, malignity, meanness, moral badness, nastiness,
   naughtiness, nefariousness, noxiousness, orneriness, peccancy,
   rankness, reprehensibility, sin, sinfulness, un-Christliness,
   unangelicalness, unchristianliness, unfavorableness, unfitness,
   unfittingness, ungodliness, unhealthiness, unholiness, unkindness,
   unlawfulness, unpleasantness, unrighteousness, unsaintliness,
   unseemliness, unskillfulness, unsuitability, vice, viciousness,
   vileness, villainousness, violation, wrong, wrongfulness,
   wrongness