crustacean crustacean /krəˈsteɪʃən/

adjective

1. Of or belonging to the class Crustacea  ( crustacean , crustaceous )
   of or belonging to the class Crustacea
   

noun

1. Any mainly aquatic arthropod usually having a segmented body and chitinous exoskeleton  ( crustacean )
   any mainly aquatic arthropod usually having a segmented body and chitinous exoskeleton