/i kuy"neuh derrm', ek"euh neuh-/ , n.
any marine animal of the invertebrate phylum Echinodermata, having a radiating arrangement of parts and a body wall stiffened by calcareous pieces that may protrude as spines and including the starfishes, sea urchins, sea cucumbers, etc.
[ 1825-35; taken as sing. of NL Echinodermata, neut. pl. of ECHINODERMATUS echîn ( os ) sea urchin + -o- -O- + -dermatos -DERMATOUS ]