A doctor who specializes in diagnosing and treating disorders of the digestive system.
digestive system (dy-JES-tiv SIS-tem)
The organs that take in food and turn it into products that the body can use to stay healthy. Waste products the body cannot use leave the body through bowel movements. The digestive system includes the salivary glands, mouth, esophagus, stomach, liver, pancreas, gallbladder, small and large intestines, and rectum.
Source: The National Cancer Institute's Dictionary of Cancer Terms (http://www.cancer.gov/dictionary)