The Collaborative International Dictionary of English v.0.48:

Crinoidea \Cri*noid"e*a\ (kr[-i]*noid"[-e]*[.a]), n. pl. [NL.,
   from Gr. kri`non lily + -oid: cf. F. crino["i]de.] (Zool.)
   A large class of Echinodermata, including numerous extinct
   families and genera, but comparatively few living ones. Most
   of the fossil species, like some that are recent, were
   attached by a jointed stem. See Blastoidea, Cystoidea,
   Comatula.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Crinoidea
    n 1: sea lilies [syn: Crinoidea, class Crinoidea]