In anatomy, a viscus ( /ˈvɪskəs/) is an internal organ, and viscera is the plural form. The viscera, when removed from a butchered animal, are known collectively as offal. Internal organs are also known as "guts" (which may also refer to the gastrointestinal tract), or more formally, "innards".
The adjective visceral, also splanchnic, is used for anything pertaining to the internal organs. Historically, viscera of animals were examined by Roman pagan priests like the haruspices or the augurs in order to divine the future by their shape, dimensions or other factors. This practice remains an important ritual in some remote, tribal societies.
The term "visceral" is contrasted with the term "parietal", meaning "of or relating to the wall of a body part, organ or cavity". The two terms are often used in describing a membrane or piece of connective tissue, referring to the opposing sides.