Echinoidea
Pronunciation : Ech`i*noi"de*a
Part of Speech : n.
Etymology : [NL. See Echinus, and -oid.] (Zo?l.)
Definition : Defn: The class Echinodermata which includes the sea urchins. They have a calcareous, usually more or less spheroidal or disk-shaped, composed of many united plates, and covered with movable spines. See Spatangoid, Clypeastroid. [Written also Echinidea, and Echinoida.]
pl.
Source : Webster's Unabridged Dictionary, 1913