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A division of the animal kingdom, including all the multicellular animal organisms in which the cells are differentiated and form tissues; distinguished from the Protozoa, or unicellular animal organisms.

met-a-z[=o]'a, n.pl. many-celled animals possessing cellular differentiation:--opp. to single-celled Protozoa.--adjs. METAZ[=O]'AN, METAZ[=O]'IC.--n.sing. MET'AZ[=O]ON. [Gr. meta, after, z[=o]on, animal.]

Animals consisting of many cells resulting from the segmentation of the ovum and comprising all phyla except the protozoa. [Gr.]