A triploblastic organism which has an internal, fluid-filled body cavity which originated from the mesoderm during embryonic development. This cavity surrounds the gut, may contain various other organs, and is called a coelom. It differs from the pseudocoels of the pseudocoelomates because it is not derived from the blastocoel. The term is used to classify multicellular animals by developmental pattern.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.