vicious

adj

1.
(of persons or their actions) able or disposed to inflict pain or suffering
barbarous brutal cruel fell roughshod savage
Derived from:
viciousness
2.
having the nature of vice
evil
Derived from:
vice viciousness
3.
bringing or deserving severe rebuke or censure
condemnable criminal deplorable reprehensible
4.
marked by deep ill will; deliberately harmful
poisonous venomous
Derived from:
viciousness