WordWeb Online

1. (of persons or their actions) able or disposed to inflict pain or suffering
   "vicious kicks";
   - barbarous, brutal, cruel, fell, roughshod, savage
    
2. Having the nature of vice
   - evil
    
3. Bringing or deserving severe rebuke or censure
   "a vicious waste of talent";
   - condemnable, criminal, deplorable, reprehensible
    
4. Marked by deep ill will; deliberately harmful
   "vicious gossip"; "took vicious pleasure in...watching me wince";
   - poisonous, venomous, viperous, malicious

See also: beady-eyed, bitchy [informal], cattish, catty, despiteful, inhumane, leering, malevolent, spiteful, venomed, vindictive, vixenish, wicked, wrong

Encyclopedia: Vicious