crustacean
UK: krʌˈsteɪʃ(ə)n | US: krʌˈsteɪʃ(ə)n
n. A primarily aquatic arthropod of the class Crustacea, characterized by a hard exoskeleton, segmented body, and jointed limbs (e.g., crabs, lobsters, shrimp).
Derived from Latin crusta ("hard shell") + -aceus (adjective-forming suffix meaning "pertaining to"). The term evolved through New Latin Crustacea (the class name) to English crustacean, reflecting the defining feature of these animals—their protective exoskeleton. The suffix -acean systematically links the word to biological classifications (e.g., Cetacean for whales).
The tidal pool teemed with tiny crustaceans like barnacles and copepods.
Lobsters are among the largest and most commercially valuable crustaceans.
Scientists study crustaceans to understand marine biodiversity.
The fossil revealed an ancient crustacean with unusually long antennae.
Many crustaceans molt their exoskeletons as they grow.