vi·cious 
(vĭshəs)
(vĭshəs)adj.
1. Mean-spirited or deliberately hurtful; malicious: vicious gossip.
2.
a. Extremely violent or injurious; cruel: a vicious blow to the stomach; vicious tactics in suppressing a rebellion.
b. Marked by an aggressive disposition. Used chiefly of animals.
c. Disposed to violent or destructive behavior: a vicious dictator.
3. Severe, powerful, or intense; fierce: a vicious storm.
4.
a. Having the nature of vice; evil, immoral, or depraved: "All men who succeed ... in finance in New York at last ... return to their native towns, assert that cities are vicious, marry their childhood sweethearts" (Sinclair Lewis).
b. Given to vice, immorality, or depravity: "The sum and substance of it was, That Oliver was a foundling, born of low and vicious parents" (Charles Dickens).
5. Faulty or defective: a forced, vicious style of prose.
[Middle English, from Old French vicieus, from Latin vitiōsus, from vitium, vice.]
vicious·ly adv.
vicious·ness n.