ivory vs nacreous

ivory

adj
  • Resembling or having the colour of ivory. 

  • Made of ivory. 

noun
  • The keys of a piano. 

  • A creamy white color, the color of ivory. 

  • The hard white form of dentin which forms the tusks of elephants, walruses and other animals. 

  • The teeth. 

  • A white person. 

  • Something made from or resembling ivory. 

  • A die (object bearing numbers, thrown in games of chance). 

nacreous

adj
  • Exhibiting lustrous or rainbow-like colors. 

  • Of, or resembling nacre (mother of pearl). 

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