medical
: a serious disease that affects the lungs and makes it difficult to breathe
He caught/contracted pneumonia over the winter.
Her father died from/of double pneumonia. [=pneumonia in both lungs]
Cite this Entry
“Pneumonia.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/pneumonia. Accessed 21 Jun. 2026.
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