heterochromatic vs two-tone

heterochromatic

adj
  • Having more than one colour; relating to heterochromia. 

  • Of light, having more than one wavelength. 

  • Of or relating to heterochromatin. 

two-tone

adj
  • Having two colours or shades. 

  • Giving two different sounds, either alternately or simultaneously. 

How often have the words heterochromatic and two-tone occurred in a corpus of books? (source: Google Ngram Viewer )