An acute or chronic inflammation of the lungs caused by viruses, bacteria or other microorganisms, or sometimes by physical or chemical irritants.

plural of pneumonia

(medicine) Pneumonia affecting one lung.

Pneumonia affecting both lungs.

plural of atypical pneumonia

An atypical pneumonia, not caused by the more traditional pathogens, and with relatively mild symptoms.

(medicine) Pneumonia not caused by one of the pathogens most commonly associated with the disease, such as Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

(pathology, virology, informal, politically offensive in Mainland China) A form of pneumonia due to infection by a coronavirus (SARS-CoV-2), which is genetically similar to SARS and MERS.

(medicine) A bacterial infection of the lungs, characteristically showing inflammation of an entire lobe.

A form of pneumonia caused by the yeast-like fungus Pneumocystis jirovecii.