collapse of all or part of a lung due to bronchial plugging or the chest cavity being opened to atomspheric pressure.
(at-uh-LEK-tuh-sis) Failure of the lung to expand (inflate) completely. This may be caused by a blocked airway, a tumor, general anesthesia, pneumonia or other lung infections, lung disease, or long-term bedrest with shallow breathing. Sometimes called a collapsed lung.