Breathing problems are a common medical issue that can range from mild to severe. Apnea, which is a five letter term, is a condition in which a person's breathing stops and starts during sleep. Asthma, a six letter term, is a chronic lung disease that causes inflammation of the airways, leading to difficulty breathing. Emphysema, a nine letter term, is a long-term lung disease that causes damage to the air sacs in the lungs, making it difficult to breathe.