The Collaborative International Dictionary of English v.0.48:

Wrongful \Wrong"ful\, a.
   Full of wrong; injurious; unjust; unfair; as, a wrongful
   taking of property; wrongful dealing. -- Wrong"ful*ly, adv.
   -- Wrong"ful*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

wrongful
    adj 1: having no legally established claim; "the wrongful heir
           to the throne" [syn: unlawful, wrongful]
    2: unlawfully violating the rights of others; "wrongful death";
       "a wrongful diversion of trust income"
    3: not just or fair; "a wrongful act"; "a wrongful charge"

Moby Thesaurus II by Grady Ward, 1.0:

82 Moby Thesaurus words for "wrongful":
   aberrant, abnormal, abominable, actionable, against the law,
   anarchic, anarchistic, anomic, atrocious, black-market, bootleg,
   chargeable, contraband, contrary to law, criminal, delinquent,
   deviant, disgraceful, evil, felonious, flawed, hardly the thing,
   ignominious, illegal, illegitimate, illicit, impermissible,
   improper, inappropriate, incorrect, indecorous, inequitable,
   infamous, iniquitous, irregular, justiciable, lawless,
   nonconstitutional, nonlegal, nonlicit, not done, not the thing,
   off-base, off-color, out-of-line, outlaw, outlawed, punishable,
   sacrilegious, scandalous, shameful, shameless, sinful, terrible,
   triable, unallowed, unauthorized, unbalanced, unconstitutional,
   under-the-counter, under-the-table, undeserved, undue, unequal,
   unequitable, uneven, unfit, unfitting, unjust, unlawful, unmeet,
   unmerited, unofficial, unrighteous, unrightful, unseemly,
   unstatutory, unsuitable, unwarrantable, unwarranted, wicked,
   wrong