/ ˈvɪʃəs; NAmE / adjective
1.
violent and cruel
SYN brutal :
a vicious attack
a vicious criminal
She has a vicious temper.
2.
( of animals ) aggressive and dangerous :
a vicious dog
3.
( of an attack, criticism, etc. ) full of hatred and anger :
She wrote me a vicious letter.
4.
( informal ) very bad or severe :
a vicious headache
a vicious spiral of rising prices
► vi·cious·ly adverb
► vi·cious·ness noun [ U ]:
Police were shocked by the viciousness of the assault.
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WORD ORIGIN
Middle English (in the sense characterized by immorality ): from Old French vicious or Latin vitiosus , from vitium vice.