COPD: Chronic obstructive pulmonary disease

Lung diseases that persistently obstruct bronchial airflow. COPD mainly involves two related diseases—chronic bronchitis and emphysema. COPD is also called chronic obstructive lung disease. Asthma is not included in COPD, as the obstruction to bronchial airflow is usually reversible and between asthma episodes the flow of air through the airways is usually good.