In anatomy of the digestive system, the cecum or caecum is a pouch connected to the large intestine between the ileum and the colon. It is separated from the ileum by the ileocecal valve (abbreviated as ICV) or Bauhin's valve, and is considered to be the beginning of the large intestine and part of the colon.

Its function is to absorb water and salts from undigested food. It has a muscular wall that can knead the contents to speed up absorption.

The cecum is present in mammals, birds and some reptiles. Herbivores have a larger cecum than humans, and exclusive carnivores have a smaller cecum or none at all.

The appendix is a branch of the cecum. Like the appendix, the cecum (from the Latin caecus meaning blind) was once believed to have no function.