Definition of pneumonia
: 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
Our Reviews team has selected the best pulse oximeters.
Love words? Need even more definitions?Merriam-Webster unabridged
Words at Play
Ask the Editors