Colectomy (ko-LEK-to-mee): An operation to remove all or part of the colon. In a partial colectomy, the surgeon removes only the cancerous part of the colon and a small amount (called a margin) of surrounding healthy tissue.

Colon resection (KO-lun ree-SEK-shun): Removal of tissue or part or all of the colon by surgery.

Anastomosis (an-AS-ta-MO-sis): A procedure to connect healthy sections of the colon or rectum after the diseased portion has been surgically removed.

Tumor (TOO-mer): An abnormal mass of tissue that results from excessive cell division. Tumors perform no useful body function. They may either be benign (not cancerous) or malignant (cancerous).

Ostomy (AHS-toe-mee): An operation to create an opening from an area inside the body to the outside.