Lung fever, also known as pneumonia, is a serious respiratory illness that affects millions of people worldwide. The condition is caused by viral, bacterial, or fungal infection that inflames the air sacs in the lungs. To avoid confusion with the antiquated term "lung fever," the medical and scientific community now use the term pneumonia to refer to the condition. Other synonymous terms for lung fever include "pneumonitis," "bronchopneumonia," and "lobar pneumonia." Each term refers to a specific type of pneumonia, depending on which part of the lungs the infection affects. Early diagnosis and treatment of lung fever, regardless of the language used to describe it, are crucial in preventing severe complications and mortality.