'polyplacophorous' originates from Greek/New Latin, specifically the Greek elements 'poly-' meaning 'many', 'plax' (or 'plak-') meaning 'plate', and '-phoros' meaning 'bearing' (through New Latin formation).

'polyplacophorous' developed from the class name 'Polyplacophora' (from Greek components 'poly-' + 'plax' + '-phoros') and was adapted into English as an adjective meaning 'bearing many plates' to describe members of that group.

Initially it meant 'bearing many plates' in a general morphological sense; over time it has been used specifically to refer to or describe molluscs of the class Polyplacophora (chitons).