ˈpɪɡ coat with a layer of copper any of various small butterflies of the family Lycaenidae having coppery wings a reddish-brown color resembling the color of polished copper uncomplimentary terms for a policeman a copper penny a ductile malleable reddish-brown corrosion-resistant diamagnetic metallic element; occurs in various minerals but is the only metal that occurs abundantly in large masses; used as an electrical and thermal conductor