achromatic vs polychromate

achromatic

adj
  • Having only the diatonic notes of the scale; not modified by accidentals. 

  • Free from color; transmitting light without color-related distortion. 

  • Containing components such as achromatic lenses and prisms, designed to prevent color-related distortion. 

  • Being achromatic in subject 

  • Uncolored; not absorbing color from a fluid; -- said of tissue 

polychromate

adj
  • Composed of many colours 

noun
  • A salt or ion composed of multiple chromate groups 

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