Definitions

1. noun

A cavity or body of fluid in an animal, especially a cavity in an embryo that gives rise to the body cavities of the adult.

“The development of the embryo’s body plan is related to the formation of the coelom, a cavity that eventually gives rise to the body cavities of the adult.”

2. noun

A fluid-filled body cavity in certain invertebrates, such as starfish or sea urchins.

“In starfish, the water vascular system is located within the coelom, a fluid-filled body cavity.”