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 first cases in the outbreak of the disease, a severe form of pneumonia, were identified in the neighborhood on July 2. Colin Mixson, New York Daily News, 14 Aug. 2026 Papa came down with pneumonia causing both lunges to collapse. Chris Biderman, Sacbee.com, 14 Aug. 2026 The Oscar-winning actress died of pneumonia on October 11, 2025. Bailey Bujnosek, InStyle, 10 Aug. 2026 Forty years later, the actor died of pneumonia at the age of 65 on April 1, 2025. Kelly Allen, PEOPLE, 9 Aug. 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 17 Aug. 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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