mono·​nu·​cle·​o·​sis ˌmä-nə-ˌnü-klē-ˈō-səs How to pronounce mononucleosis (audio)
: an abnormal increase of mononuclear white blood cells in the blood
specifically : infectious mononucleosis

Example Sentences

Recent Examples on the Web Pneumonia, the flu, Covid-19, tuberculosis, mononucleosis, and HIV are infections that might increase sweating. Erica Sweeney, Men's Health, 11 Nov. 2022 On Monday morning at the Comerica Center in Frisco, Stars defenseman Miro Heiskanen skated for the first time since his mononucleosis diagnosis nearly two weeks ago. Dallas News, 22 Mar. 2022 In their report, the team stressed that EBV alone is not enough to trigger MS; over 90 percent of humans get the virus, which sometimes causes mononucleosis, by early adulthood. Kenneth Miller, Discover Magazine, 8 Dec. 2022 Heiskanen missed the second meeting with mononucleosis. Dallas News, 20 Apr. 2022 Some evidence suggests that prior infection with Epstein-Barr virus (EBV), which causes mononucleosis, puts people at higher risk for developing long Covid. Marla Broadfoot, Smithsonian Magazine, 19 Aug. 2022 That was the game where Fredette, still recovering from mononucleosis, had 33 of BYU’s 71 points; a sign in the student section asked which one of his wives gave it to him. Mark Zeigler, San Diego Union-Tribune, 10 Nov. 2022 With leading scorer and three-point shooter Will Richardson out again due to mononucleosis, there was no overcoming that deficiency. oregonlive, 19 Mar. 2022 The virus can cause mononucleosis and, according to some researchers, Chronic Fatigue Syndrome—which, similar to long COVID, includes symptoms like fatigue, concentration problems, and headaches. Erin Prater, Fortune, 3 July 2022 See More

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.

Word History


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

First Known Use

1907, in the meaning defined above

Time Traveler
The first known use of mononucleosis was in 1907

Dictionary Entries Near mononucleosis

Cite this Entry

“Mononucleosis.” Dictionary, Merriam-Webster, Accessed 29 Jan. 2023.

Medical Definition


mono·​nu·​cle·​o·​sis -ˌn(y)ü-klē-ˈō-səs How to pronounce mononucleosis (audio)
: an abnormal increase of mononuclear white blood cells in the blood
specifically : infectious mononucleosis

More from Merriam-Webster on mononucleosis

Last Updated: - Updated example sentences
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