mono·​nu·​cle·​o·​sis | \ ˌmä-nə-ˌnü-klē-ˈō-səs How to pronounce mononucleosis (audio) , -ˌnyü- \

Definition of mononucleosis

: an abnormal increase of mononuclear white blood cells in the blood specifically : infectious mononucleosis

Examples of mononucleosis in a Sentence

Recent Examples on the Web But Buckingham got mononucleosis, which delayed their L.A. sojourn by the better part of a year, during which Nicks took care of him and the two continued to grow musically. Los Angeles Times, 10 Sep. 2021 Only after consulting with several doctors over many months was he diagnosed with mononucleosis and anemia. Joshua Robinson, WSJ, 30 Jan. 2021 Doctors see similarities between long Covid and what can happen after mononucleosis or in other post-viral syndromes. Elizabeth Cooney, STAT, 12 June 2021 The fourth-year quarterback, who just turned 24 on Saturday, infamously dealt with mononucleosis, another infectious illness, two seasons ago with the New York Jets. Anthony Rizzuti, USA TODAY, 9 June 2021 After being misdiagnosed with mononucleosis, Ms. Cormier said emergency room doctors then told her there was nothing wrong with her. New York Times, 4 June 2021 The frontcourt will also feature one of just three returners who played last season in sophomore Jalen Graham, who improved tremendously late in the season after being sidelined with mononucleosis. Michelle Gardner, The Arizona Republic, 22 Apr. 2021 For example, the Epstein-Barr virus, best known for causing mononucleosis, has been linked to lupus and other autoimmune diseases. Liz Szabo, USA TODAY, 3 Mar. 2021 Covid-19 cause other dormant viruses, like the Epstein-Barr virus, which causes mononucleosis, or shingles to activate? Sumathi Reddy, WSJ, 25 Jan. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'mononucleosis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of mononucleosis

1907, in the meaning defined above

History and Etymology for mononucleosis

New Latin, from International Scientific Vocabulary mononuclear + New Latin -osis

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Time Traveler for mononucleosis

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The first known use of mononucleosis was in 1907

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Last Updated

25 Sep 2021

Cite this Entry

“Mononucleosis.” Dictionary, Merriam-Webster, Accessed 27 Sep. 2021.

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English Language Learners Definition of mononucleosis

: a disease that makes people very tired and weak for a long time


mono·​nu·​cle·​o·​sis | \ -ˌn(y)ü-klē-ˈō-səs How to pronounce mononucleosis (audio) \

Medical Definition of mononucleosis

: an abnormal increase of mononuclear white blood cells in the blood specifically : infectious mononucleosis

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