mono·​nu·​cle·​o·​sis | \ -ˌnü-klē-ˈō-səs , -ˌnyü-\

Definition of mononucleosis

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

Examples of mononucleosis in a Sentence

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But with Pete Nance sidelined indefinitely because of mononucleosis, Falzon came through in a big way. Andrew Seligman, The Seattle Times, "Falzon scores 21, Northwestern beats Indiana 73-66," 22 Jan. 2019 The Tigers will be without freshman closer Cody Greenhill due to mononucleosis, and left-handed reliever Andrew Mitchell could be sidelined after undergoing an MRI on Thursday due to forearm tightness. Tom Green,, "No. 13 Auburn baseball ready for tough SEC slate, starting with No. 10 Texas A&M," 16 Mar. 2018 But Howell’s fierce attitude was no match for battles with appendicitis and mononucleosis that affected him during the past school year. Dave Melton, Post-Tribune, "Mr. Happy Go Lucky: Metea Valley grad Christian Howell keeps it loose and throws strikes for Northwest Indiana Oilmen," 14 July 2018 Auburn closer Cody Greenhill inching closer to return to bullpen after bout with mononucleosisBullpen help could soon be on the way for No. Creg Stephenson,, "Johnny Manziel to participate in Texas A&M Pro Day on Tuesday," 26 Mar. 2018 Symptoms of mononucleosis include a sore throat, enlarged tonsils, laryngitis, swollen lymph nodes in the neck or armpits, fever, head and body aches. New York Times, "My Daughter Has Mono. Is the Whole Family at Risk?," 29 June 2018 Early assessment: Got off to a great start but then missed about two months because of mononucleosis. Helene St. James, Detroit Free Press, "Detroit Red Wings 2017 NHL draft: Michael Rasmussen looks promising," 16 June 2018 After missing a significant portion of the season with mononucleosis, Richardson had been struggling at the plate and was pressing. Andrew Hussey, Indianapolis Star, "Grant Richardson is the missing piece behind Fishers' run to the state championship game," 13 June 2018 After starting the year slowly because of a December battle with mononucleosis, and after struggling with his putter, Spieth is in fine form. Steve Dimeglio, USA TODAY, "Jordan Spieth writes his own path to PGA Tour," 16 May 2018

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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Last Updated

7 Feb 2019

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Time Traveler for mononucleosis

The first known use of mononucleosis was in 1907

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English Language Learners Definition of mononucleosis

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


mono·​nu·​cle·​o·​sis | \ -ˌn(y)ü-klē-ˈō-səs \

Medical Definition of mononucleosis

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

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