Arthropod

Part of speech: noun

Pronunciation: /ˈɑːθɹəpɒd/

Definitions

1. An invertebrate creature distinguished by its segmented structure, jointed limbs, and an exoskeleton composed of chitin
2. A member of the invertebrates that possesses a body plan with segmentation, articulated appendages, and a protective chitinous outer layer
3. An invertebrate animal characterized by a segmented body, jointed appendages, and a chitinous exoskeleton

Etymology: Arthropods are the animals with jointed legs, and their name is a plain piece of Greek. "Arthron" meant "joint" and "pous" meant "foot," so the word literally means "jointed foot." Taxonomists built it in New Latin, the scientific Latin used for naming organisms, by joining the Greek parts into "Arthropoda" as the name of the group, and English later took the term from that. The Greek pieces are worth a closer look because they recur across biology. "Arthro-" appears in arthritis, where it refers to inflamed joints, and "-pod" appears in words like "tripod" and "octopod," where it marks a creature by its feet. The name therefore describes the animal's most visible trait, its articulated limbs, rather than its shell or body plan, which is how many earlier descriptions had grouped these creatures.

Synonyms: insect, spider, crustacean, myriapod, arachnid