Metazoa Met·a·zo·a (mět'ə-zō'ə)n. A subdivision of the animal kingdom that includes all multicellular animal organisms having cells that are differentiated and form tissues and organs.
Any of the animals belonging to the subkingdom Metazoa, having a body made up of differentiated cells arranged in tissues and organs. All multicellular animals besides sponges are metazoans.
A multicellular animal. No longer in scientific use.