Reflux, esophageal: A condition wherein stomach contents regurgitate or back up (reflux) into the esophagus (a long cylindrical tube that transports food from the mouth to the stomach). The food in the stomach is partially digested by stomach acid and enzymes. Normally, the partially digested acid content in the stomach is delivered by the stomach muscle into the small intestine for further digestion. In esophageal reflux, stomach acid content refluxes backwards up into the esophagus, occasionally reaching the breathing passages, causing inflammation and damage to the esophagus, as well as to the lung and larynx (the voice box). The overall process is medically termed gastroesophageal reflux disease (GERD). 10% of patients with GERD develop a Barrett's esophagus which can increase the risk of cancer of the esophagus.