In anatomy, the anus (from Latin ānus "ring (circle) , anus") is the external opening of the rectum. Closure is controlled by sphincter muscles. Feces are expelled from the body through the anus during the act of defecation, which is the primary function of the anus. Most animals — from simple worms to elephants and humans — have a tubular gut, with a mouth at one end and an anus at the other.
The anus plays a role in sexuality, though attitudes towards anal sex vary and it is even illegal in some countries. The anus is also the site of potential infections and other conditions including cancer. The subject is often considered a taboo part of the body, and is known by a large number of usually vulgar slang terms. The traditional polite synonym for anus was fundament, though this euphemism is rarely heard now that medical terms are widely acceptable.
