The anus (, which is from Proto-Indo-European *h1eh2no-, meaning "ring") is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may include: matter which the animal cannot digest, such as bones; food material after all the nutrients have been extracted, for example cellulose or lignin; ingested matter which would be toxic if it remained in the digestive tract; and dead or excess gut bacteria and other endosymbionts.

Anusim (, ; singular male, Anús, ; singular female, Anusáh, , meaning "Coerced [converted Jews]") is a legal category of Jews in halakha (Jewish law) who were forced to abandon Judaism against their will, typically while forcibly converted to another religion. The term "anusim" is most properly translated as the "coerced [ones]" or the "forced [ones]".