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.
Legionnaires' disease is a severe form of pneumonia that is caused by inhaling the Legionella bacteria in small droplets of water mixed in the air or contaminated water accidentally going into the lungs. Mary Kekatos, ABC News, 31 July 2026 Murphy, who played Tai Frasier in the film, died in 2009 from pneumonia at age 32. Brendan Morrow, USA Today, 30 July 2026 Late in June, and training in his record-breaking trainer Cherie DeVaux’s native Saratoga while being aimed for the Jim Dandy and the Travers, Golden Tempo came down with a case of pneumonia. Guy Martin, Forbes.com, 29 July 2026 Measles hospitalizes nearly 10% of its victims and causes pneumonia, sepsis and potentially fatal encephalitis. Dr. Michael Good, Hartford Courant, 26 July 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 4 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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