bronchiolitis obliterans syndrome (Monarch Disease Ontology entry MONDO_0015265) can be described as follows. A lung disorder that is mainly associated with chronic allograft dysfunction after lung transplantation and that is characterized by inflammation and fibrosis of bronchiolar walls that reduce the diameter of the bronchioles and result in progressive and irreversible airflow obstruction. Also known as: BOOP, bronchiolitis fibrosa obliterans, constrictive bronchiolitis, organised pneumonia, organized pneumonia.