(Science: anatomy, gastroenterology) The most dilated portion of the digestive tube, situated between the oesophagus and the beginning of the small intestine (duodenum). It lies in the upper central portion of the abdomen (above the umbilicus) and to the left of the midline. The stomach produces gastric juice (acidic) which serves to breakdown proteins. An enlarged and muscular saclike organ of the alimentary canal; the principal organ of digestion.The region of the body of a vertebrate between the thorax and the pelvis.The region of the body of a vertebrate between the thorax and the pelvis.Part of the vertebrate digestive system where powerful digestive enzymes are secreted into it to assist in the breakdown of foodstuff that has been freshly eaten. Essentially, the stomach prepares the food before it can be transported to the duodenum, the upper part of the small intestine.