monovalent vs pristine

monovalent

adj
  • univalent. 

noun
  • Any univalent substance. 

pristine

adj
  • Unspoiled; still with its original purity; uncorrupted or unsullied. 

  • Perfect. 

  • Primitive, pertaining to the earliest state of something. 

  • Relating to sawfishes of the family Pristidae. 

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