bluish vs polychromate

bluish

adj
  • Having a tint or hue similar to the colour blue. 

  • Somewhat depressed; sad. 

polychromate

adj
  • Composed of many colours 

noun
  • A salt or ion composed of multiple chromate groups 

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