Gastroparesis: A disease of the muscles of the stomach or the nerves controlling the muscles that causes the muscles to stop working. Gastroparesis results in inadequate grinding of food by the stomach and poor emptying of food from the stomach into the intestine. Gastroparesis may be associated with paralysis of the small intestine and colon. The most common underlying cause is diabetes mellitus. Gastroparesis is diagnosed via gastric emptying study. It is usually treated with medications that stimulate the stomach muscle to contract.