Colitis: Inflammation of the large intestine (the colon). There are many forms of colitis, including ulcerative colitis, Crohn’s disease, infectious, pseudomembranous, and spastic. For example, intermittent rectal bleeding, crampy abdominal pain and diarrhea can be symptoms of ulcerative colitis. Diagnosis can be made by direct visualization using (sigmoidoscopy or colonoscopy) which is the most accurate test. Long-standing ulcerative colitis increases the risk for colon cancer. Ulcerative colitis can also be associated with inflammation in joints, spine, skin, eyes, the liver and its bile ducts. Treatment of ulcerative colitis can involve medications and surgery.