clayey vs difficult

clayey

adj
  • Resembling clay; claylike, clayish. 

  • Of the human body, as contrasted with the soul; bodily, human, mortal. 

  • Covered or dirtied with clay. 

  • Composed of clay or containing (much) clay; clayish. 

difficult

adj
  • Hard to manage, uncooperative, troublesome. 

  • Hard, not easy, requiring much effort. 

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