cupreous vs cupric

cupreous

adj
  • Of or of the nature of copper. 

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

  • Containing copper. 

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

cupric

adj
  • Of, pertaining to, or derived from, copper; containing copper. 

  • Containing copper with an oxidation number of 2 

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