Pla·coph′o·ra (plȧ·kŏf′ō·rȧ), n. pl. [NL., from Gr. πλάξ, πλακός, tablet + φέρειν to bear.] (Zoöl.) A division of gastropod Mollusca, including the chitons. The back is covered by eight shelly plates. Called also Polyplacophora. See Illust. under Chiton, and Isopleura.