http://www.nhlbi.nih.gov/health/dci/Diseases/brn/brn_whatis.html
National Heart, Lung, and Blood Institute, National Institutes of Health
Bronchiectasis is a lung disease that usually results from an infection or other condition that injures the walls of the airways in your lungs. This injury is the beginning of a cycle in which your airways slowly lose their ability to clear out mucus. The mucus builds up and creates an environment in which bacteria can grow. This leads to repeated serious lung infections. Each infection causes more damage to your airways.