The Oxford Thesaurus An A-Z Dictionary of Synonyms - vicious adj.

1) immoral, unprincipled, amoral, barbarous, corrupt, evil, bad, base, depraved, vile, atrocious, execrable, degraded, degrading, degenerate, venal, iniquitous, heinous, odious, perverted, nefarious, wicked, flagitious, devilish, diabolic(al) , fiendish, monstrous, profligate, shameful, shameless, abominable, sinful: The vicious, bloody dictatorship on the island lasted only a dozen years. 2) malicious, spiteful, mean, nasty, hateful, malevolent, malignant, bitter, acrimonious, rancorous, venomous, vindictive, defamatory, slanderous, scandalous, Slang rotten, bitchy: When they argued, they said terribly vicious things to one another. 3) savage, wild, untamed, ferocious, fearful, brutal, fierce, fiendish, bestial, feral, brutish, ravening, Literary fell: The local children were terrified of his vicious Rottweiler.