copper vs cupreous

copper

adj
  • Having the reddish-brown colour/color of copper. 

  • Made of copper. 

verb
  • To sheathe or coat with copper. 

noun
  • The reddish-brown colour/color of copper. 

  • A police officer. 

  • A reddish-brown, malleable, ductile metallic element with high electrical and thermal conductivity, symbol Cu, and atomic number 29. 

  • Any of various lycaenid butterflies with copper-coloured upperwings, especially those of the genera Lycaena and Paralucia. 

cupreous

adj
  • Of a reddish-brown color, like that of polished copper. 

  • Of or of the nature of copper. 

  • Containing copper. 

noun
  • A reddish-brown color, like that of polished copper. 

How often have the words copper and cupreous occurred in a corpus of books? (source: Google Ngram Viewer )