Pneumonia - Definition
Pneumonia (pronounced noo-MOAN-ya) is an infection of the lung. It can be caused by a great many different agents, including bacteria, viruses, fungi, and parasites. In the United States, pneumonia is the sixth most common disease leading to death. It is also the most common fatal infection acquired by patients in hospitals. In developing countries, pneumonia is one of the two most common causes of death. Diarrhea is the other.