Asterioidea \As*te`ri*oid"e*a\, Asteridea \As`ter*id"e*a\, n.
pl. [NL., fr. Gr. 'asteri`as + -oid. See {Asterias}.] (Zool.)
A class of Echinodermata including the true starfishes. The
rays vary in number and always have ambulacral grooves below.
The body is star-shaped or pentagonal.
[1913 Webster]