The definition of a crustacean is an arthropod with a hard outer shell and jointed limbs that usually lives in aquatic environments.(noun)
A lobster is an example of a crustacean.
See crustacean in Webster's New World College Dictionary
Origin: ModL Crustacea < crustaceus, having a crust or shell < L crusta, crust
See crustacean in American Heritage Dictionary 4
Origin: From New Latin Crūstācea, class name, neuter pl. of crūstāceus, hard-shelled, from Latin crūsta, shell; see kreus- in Indo-European roots.
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