crinoidPronunciation: /ˈkrʌɪnɔɪd, ˈkrɪnɔɪd/ ZoologyDefinition of crinoid noun an echinoderm of the class Crinoidea, which comprises the sea lilies and feather stars. adjective relating to or denoting crinoids. Derivatives crinoidalPronunciation: /-ˈnɔɪd(ə)l/ adjective crinoid in other Oxford dictionaries Definition of crinoid in the US English dictionary