Eructation is the medical term for belching or belching. It is the act of expelling gas from the stomach through the mouth. Belching, also known as burping, is a common digestive symptom that occurs when air is expelled from the stomach through the mouth. Belching is usually caused by swallowing excess air while eating or drinking. Belching can also be caused by certain medical conditions such as gastroesophageal reflux disease (GERD).