multichromatic vs polychromic

multichromatic

adj
  • Involving more than one colour. 

polychromic

adj
  • Polychromatic; many-coloured. 

  • Pertaining to, or designating, any one of several acids (known only in their salts) which contain more than one atom of chromium. 

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