Borborygmus (plural borborygmi) (pronounced [ˌborbərˈɪɡməs]) (from Greek βορβορυγμός) also known as stomach growling, or rumbling, is the rumbling sound produced by the movement of gas through the intestines of animals, including humans. The word borborygmus is an onomatopoeia for this rumbling.

The "rumble" or "growl" sometimes heard from the stomach is a normal part of digestion. It originates in the stomach or upper part of the small intestine as muscles contract to move food and digestive juices down the gastrointestinal tract and functions as a sort of intestinal "housecleaning". Sometimes it occurs as part of the migrating myoelectric complex.

Although this muscle contraction happens whether or not food is present, it is more common after the animal has gone several hours without eating. This may be why a "growling" stomach is often associated with hunger.

Rumbles may also occur when there is incomplete digestion of food that can lead to excess gas in the intestine (sometimes known as "bubble guts"). In humans this can be due to incomplete digestion of carbohydrate-containing foods including milk and other dairy products (lactose intolerance or the use of α-glucosidase inhibitors by diabetics), gluten (protein in wheat, barley, and rye) (celiac disease), fruits, vegetables, beans, legumes, and high-fiber whole grains. In rare instances excessive abdominal noise may be a sign of digestive disease, especially when accompanied by abdominal bloating, abdominal pain, diarrhoea or constipation. Some examples of diseases that may be associated with this symptom include carcinoid neoplasm and celiac sprue.