GERD stands for gastroesophageal (say: gass-troh-eh-soff-eh-JEE-el) reflux (say: REE-fluks) disease.
Gastroesophageal reflux (GER) is when food and acid from the stomach go back up into the esophagus. This causes an uncomfortable feeling in the chest, often called heartburn.
Reflux that happens a lot and causes problems like poor growth, vomiting, or damage to the esophagus is called GERD. It's more serious than GER and is usually treated with medicine.