Echinodermata \E*chi`no*der"ma*ta\ ([-e]*k[imac]`n[-o]*d[~e]r"m[.a]*t[.a]), n. pl. [NL., fr. Gr. 'echi^nos hedgehog, sea urchin + de`rma, -atos, skin.] (Zo["o]l.) One of the grand divisions of the animal kingdom. By many writers it was formerly included in the Radiata. [Written also {Echinoderma}.]