copper: [OE] A major source of copper in the ancient world was the Mediterranean island of Cyprus, so the Romans called it cyprium aes ‘metal of Cyprus’. This became cuprum in late Latin, from which it was borrowed into prehistoric West and North Germanic as *kupar, source of Old English coper. (Copper the slang term for ‘policeman’ [19] is simply the agent noun formed from the verb cop ‘seize’, which probably comes via Old French caper from Latin capere ‘seize, take’, source of English capture.)
