pneumonia

noun

: an acute disease that is marked by inflammation of lung tissue accompanied by infiltration of alveoli and often bronchioles with white blood cells (such as neutrophils) and fibrinous exudate, is characterized by fever, chills, cough, difficulty in breathing, fatigue, chest pain, and reduced lung expansion, and is typically caused by an infectious agent (such as a bacterium, virus, or fungus) see bronchopneumonia, pneumocystis carinii pneumonia, primary atypical pneumonia compare pneumonitis

Examples of pneumonia in a Sentence

He caught pneumonia over the winter.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The viral disease causes a blotchy rash and flulike symptoms but can develop into severe, life-threatening illnesses, such as pneumonia and brain swelling. Lauren J. Young, Scientific American, 18 Sep. 2026 Coroner’s records list Isaiah’s cause of death as a bacterial infection resulting from pneumonia, but other significant factors included blunt force trauma injuries and the impacts of long-term restraint. Rebecca Ellis, Los Angeles Times, 18 Sep. 2026 Though most people with pneumonia, an inflammation of the lungs usually caused by infection, won’t develop sepsis, the Sepsis Alliance states that the most common source of the condition among adults is the lungs. Adam England, PEOPLE, 17 Sep. 2026 The report from the Putnam County Coroner’s office also lists acute pneumonia and previous myocardial infarction as contributing factors. Brian Niemietz, New York Daily News, 15 Sep. 2026 See All Example Sentences for pneumonia

Word History

Etymology

New Latin, from Greek, from pneumōn lung, alteration of pleumōn — more at pulmonary

First Known Use

1603, in the meaning defined above

Time Traveler
The first known use of pneumonia was in 1603

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Cite this Entry

“Pneumonia.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pneumonia. Accessed 19 Sep. 2026.

Kids Definition

: a disease of the lungs marked by inflammation, congestion, fever, cough, and difficulty in breathing and caused especially by infection

Medical Definition

: an acute disease that is marked by inflammation of lung tissue accompanied by infiltration of alveoli and often bronchioles with white blood cells (as neutrophils) and fibrinous exudate, is characterized by fever, chills, cough, difficulty in breathing, fatigue, chest pain, and reduced lung expansion, and is typically caused by an infectious agent (as a bacterium, virus, or fungus) see bronchopneumonia, lobar pneumonia, pneumocystis carinii pneumonia, primary atypical pneumonia

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