A congenital condition in which a mass of nonfunctioning lung tissue lacks a normal connection with the tracheobroncheal tree and receives an anomalous blood supply from a systemic branch of the thoracic aorta originating from the descending thoracic or abdominal aorta: The bronchopulmonary sequestration may be extralobar; that is, completely separated from the normally connected lung, or intralobar, which is partly surrounded by a normal lung.