mottled vs polychromatic

mottled

adj
  • Colored in patches; spotted. 

polychromatic

adj
  • Showing a variety, or a change, of colours; having many colours; multicoloured. 

  • Composed of more than one wavelength. 

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