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bug

noun [C] (ILLNESS)
 
 
/bʌɡ/ informal

Definition

B2 a bacteria or a virus causing an illness that is usually not serious: I had a tummy/stomach bug last week. There's a bug going around (= an illness that many people are getting).Bacteria, moulds, germs and viruses
(Definition of bug noun (ILLNESS) from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

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