copper vs embrown

copper

verb
  • To sheathe or coat with copper. 

adj
  • Made of copper. 

  • Having the reddish-brown colour/color of 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. 

embrown

verb
  • To make (something) dark or dusky (“having a rather dark shade of colour”); to brown, to darken. 

  • To make (something) brown; to brown. 

  • To become or make dark or dusky; to brown, to darken. 

  • To become or make brown; to brown. 

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