butyric vs unctuous

butyric

adj
  • Of, pertaining to, or characteristic of butter 

  • Of, pertaining to, or derived from butyric acid or any of the isomeric univalent radicals of formula C₃H₇CO₂- 

unctuous

adj
  • Oily or greasy. 

  • Rich, lush, intense, with layers of concentrated, soft, velvety flavor. 

  • Profusely polite, especially unpleasantly so and insincerely earnest. 

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