n pl :  a phylum of invertebrate animals (as insects, arachnids, and crustaceans) having a segmented body and jointed appendages, usu. a shell of chitin molted at intervals, and an anterior brain dorsal to the alimentary canal and connected with a ventral chain of ganglia ar*thro*pod adj or n ar*throp*o*dan adj 
 
 
 
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