an extinct cephalopod mollusc with a bullet-shaped internal shell that is typically found as a fossil in marine deposits of the Jurassic and Cretaceous periods.
Order Belemnoidea, class Cephalopoda: many genera
Origin:
early 17th century: from modern Latin belemnites, based on Greek belemnon 'dart'
belemnite in other Oxford dictionaries
Definition of belemnite in the US English dictionary
