auburn vs red-brown

auburn

adj
  • Of a reddish-brown colour. 

noun
  • A dark reddish-brown colour, often used to describe hair colour. 

red-brown

adj
  • Having a colour between red and brown. 

  • Having the qualities of fascism and communism. 

How often have the words auburn and red-brown occurred in a corpus of books? (source: Google Ngram Viewer )