Definition of pentacrinite in US English:

pentacrinite

noun

rare
  • A fossil crinoid of the genus Pentacrinus or family Pentacrinitidae, having a five-sided stalk and a calyx consisting of five plates, and known from remains of the Jurassic period.

Origin

Early 19th century. From scientific Latin Pentacrinus, genus name + -ite.

Pronunciation

pentacrinite

/pɛnˈtakrɪnʌɪt/