The anal canal is a part of the human anatomy that is often associated with embarrassment and discomfort. There are several synonyms that can be used for this term, which include rectal passage, rectal canal, and anus. The rectal canal is the part of the large intestine that connects the rectum to the anus. This canal is responsible for eliminating waste material from the body. The anus, on the other hand, is the external opening of the rectum and is the site of waste elimination from the body. While these terms have slightly different meanings, they can be used interchangeably in medical discussions.