'unplated' originates from English, combining the prefix 'un-' (from Old English 'un-') meaning 'not' and the root 'plate' which comes from Old French 'plate' (via Late Latin 'platta' from Greek 'platys'), where 'platys' meant 'broad, flat'.

'plate' entered English from Old French 'plate' into Middle English 'plate' and eventually became the modern English 'plate'; the negative prefix 'un-' has been used in English since Old English to form opposites, producing the compound 'unplated'.

Initially it was a straightforward negative of 'plate' meaning 'not plated'; over time it has retained that core meaning for the adjective and came to be used as the past/past-participle form of the verb 'unplate' meaning 'removed plating'.