The Collaborative International Dictionary of English v.0.48:

Wrongdoing \Wrong"do`ing\, n.
   Evil or wicked behavior or action.
   [1913 Webster]

WordNet (r) 3.0 (2006):

wrongdoing
    n 1: departure from what is ethically acceptable [syn: error,
         wrongdoing]
    2: activity that transgresses moral or civil law; "he denied any
       wrongdoing" [syn: wrongdoing, wrongful conduct,
       misconduct, actus reus]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "wrongdoing":
   amorality, backsliding, bad policy, badness, carnality, crime,
   criminality, delict, delinquency, diablerie, discourtesy, disorder,
   disorderliness, disorderly conduct, disruption, disruptiveness,
   evil, evil nature, felony, frowned-upon behavior, hooliganism,
   horseplay, illegality, immorality, impolicy, impropriety, impurity,
   inexpedience, inexpediency, iniquity, maladministration,
   malfeasance, malpractice, misadministration, misbehavior,
   misconduct, misdemeanor, misdirection, misdoing, misfeasance,
   misgovernment, misguidance, mishandling, mismanagement, misrule,
   moral delinquency, naughtiness, neglect, negligence, nonfeasance,
   nonsanctioned behavior, offense, omission, peccability,
   prodigality, recidivism, roughhouse, rowdiness, rowdyism,
   ruffianism, sin, tort, unangelicalness, unchastity, uncleanness,
   ungodliness, ungoodness, unmorality, unrighteousness,
   unsaintliness, unvirtuousness, vandalism, venial sin, vice,
   viciousness, violation, wantonness, waywardness, wrong