1. A fluid-filled body cavity in animals that lies between the outer body wall and the digestive tract, lined with mesoderm.
Usage: biology; also spelled 'coelom'

Examples

• The celom in earthworms is divided into segments by partitions called septa.
• In vertebrates, the celom is subdivided into the pericardial, pleural, and peritoneal cavities.
• The development of a true celom was an important evolutionary advancement in animal body plans.
• Organs within the celom are protected and can move freely within the fluid-filled space.
• The lining of the celom, called the peritoneum, secretes fluid that reduces friction between organs.