Sigmoidoscopic refers to a diagnostic procedure where a doctor uses a flexible, lighted instrument called a sigmoidoscope to examine the lower portion of the colon. While the term sigmoidoscopic is specific to this particular medical procedure, there are other synonyms that can be used to describe it. Some of these synonyms include colonoscopy, rectoscopy, proctoscopy, and endoscopy. Each of these terms refers to a slightly different type of diagnostic procedure used to examine different parts of the colon or rectum. However, they all involve the use of a specialized medical instrument to visually assess the interior of the intestine.