[vi.cious] adj [ME, fr. MF vicieus, fr. L vitiosus full of faults, corrupt, fr. vitium vice] (14c) 1: having the nature or quality of vice or immorality: depraved
2: defective, faulty; also: invalid
3: impure, noxious
4. a: dangerously aggressive: savage "a ~ dog" b: marked by violence or ferocity: fierce "a ~ fight"
5: malicious, spiteful "~ gossip"
6: worsened by internal causes that reciprocally augment each other "a ~ wage-price spiral" -- vi.cious.ly adv -- vi.cious.ness n syn vicious, villainous, iniquitous, nefarious, corrupt, degenerate mean highly reprehensible or offensive in character, nature, or conduct. vicious may directly oppose virtuous in implying moral depravity, or may connote malignancy, cruelty, or destructive violence "a vicious gangster". villainous applies to any evil, depraved, or vile conduct or characteristic "a villainous assault". iniquitous implies absence of all signs of justice or fairness "an iniquitous system of taxation". nefarious suggests flagrant breaching of time-honored laws and traditions of conduct "the nefarious rackets of organized crime". corrupt stresses a loss of moral integrity or probity causing betrayal of principle or sworn obligations "city hall was rife with corrupt politicians". degenerate suggests having sunk to an esp. vicious or enervated condition "a degenerate regime propped up by foreign powers".