ˌkrəˈstāsh(ē)ə noun plural
Etymology: New Latin, from neuter plural of crustaceus crustaceous
1. capitalized : a large class of Arthropoda comprising the majority of the marine or freshwater arthropods (as lobsters, shrimps, crabs, water fleas, and barnacles) and some terrestrial forms (as the wood lice) all having a body that is divided into segments of head, thorax, and abdomen of which the first two often consolidate into a cephalothorax and that is enclosed in a chitinous integument often hardened with calcareous matter into a firm exoskeleton, having a pair of appendages which are variously differentiated into mouthparts, walking legs, and swimmerets associated with each segment, and having two pairs of antennae — compare branchiopoda , cirripedia , copepoda , malacostraca , trilobita
2. : members of the class Crustacea : crustaceans