An influenza is a contagious viral infection. Influenzas tend to spread during the winter, and they're more commonly known as the flu.

If you've ever wondered why this word looks so much like influence, that’s because both come from the Italian influentia. The original idea was a flowing in — of ethereal fluid from the heavens, thus affecting human destiny. We know now influenza is caused by viruses, not heavenly fluid. When you have an influenza, you're likely to vomit, have diarrhea, be exhausted, and feel terrible overall. One way to prevent influenza is by getting a flu shot.

Definitions of influenza
  1. noun
    an acute febrile highly contagious viral disease
    synonyms: flu, grippe
    see moresee less
    Asian influenza, Asiatic flu
    influenza caused by the Asian virus that was first isolated in 1957
    swine flu, swine influenza
    an acute and highly contagious respiratory disease of swine caused by the orthomyxovirus thought to be the same virus that caused the 1918 influenza pandemic
    type of:
    contagion, contagious disease
    any disease easily transmitted by contact
    respiratory disease, respiratory disorder, respiratory illness
    a disease affecting the respiratory system
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