Final answer:
The term for visual examination of the sigmoid colon is sigmoidoscopy, which is used to inspect the rectum and lower third of the colon for potential colorectal cancer but does not examine the entire colon like a colonoscopy does.
Step-by-step explanation:
The word meaning visual examination of the sigmoid colon is a) Sigmoidoscopy. This medical procedure allows a doctor to inspect the rectum and the lower third of the colon using a small camera. This area is where the majority of cases of colorectal cancer occur. However, it is important to note that sigmoidoscopy does not allow for examination of the entire colon. For a full inspection, a colonoscopy may be necessary. This involves the use of a camera at the end of a long tube which is inserted into the colon, allowing the doctor to visualize the large intestine's lining for detection of cancerous lesions or polyps. A colonoscopy is the gold standard for diagnosing colorectal cancer and can also help prevent cancer by enabling the removal of potentially pre-cancerous polyps.