Definition of: vicious

(vish′əs) adjective
1. Addicted to vice; corrupt in conduct or habits; wicked; depraved.
2. Partaking of what is base, low, and vile; morally injurious; evil.
3. Unruly or dangerous; refractory, as an animal.
4. Defective or faulty: vicious arguments.
5. Impure or incorrect: corrupted, as a text, manuscript, etc.
6. Noxious; poisonous; foul, as water, air, etc.
7. Colloq. Marked by malice or spite; malignant: a vicious lie. See synonyms under CRIMINAL, IMMORAL, IRREGULAR, RESTIVE. [<OF <L vitiosus <vitium a fault]
—vi′cious·ly adverb
—vi′cious·ness noun