splanchnocœle

from The Century Dictionary.

• noun A visceral cavity; specifically, the visceral cavity of a brachiopod, an anterior division of which is the brachiocœle or brachial chamber, and the lateral parts of the posterior division of which are the pleurocœles.
• noun In embryology, the portion of the body-cavity lying between the somatopleure and splanchnopleure of the vertebrate embryo and persisting in the adult as the pleuroperitoneal cavity.