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English definition of “mononucleosis”

mononucleosis

noun [U]  /ˌmɑn·əˌnu·kliˈoʊ·sɪs/ (short form mono) us  
a disease that causes a sudden fever, swelling of organs that produce white blood cells, and a sore throat, and which can make a person feel weak and ill for a long time
(Definition of mononucleosis from the Cambridge Academic Content Dictionary © Cambridge University Press)
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