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English definition of “virus”

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virus

noun [C] uk   /ˈvaɪə.rəs/ us    /ˈvaɪ-/

virus noun [C] (DISEASE)

B2 an extremely small piece of organic material that causes disease in humans, animals, and plants: a chickenpox/flu/herpes/mumps virus Evidence suggested that the AIDS virus was spreading very quickly among the heterosexual community.B2 a disease caused by a virus: I don't know exactly what's wrong with her - I think it's some sort of virus.
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virus noun [C] (COMPUTER PROBLEM)

B1 a computer program or part of a computer program that can make copies of itself and is intended to prevent the computer from working normally
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(Definition of virus from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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