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]