centrifugal vs mysterious

centrifugal

adj
  • Tending, or causing, to recede from the center. 

  • Expanding first at the summit, and later at the base, as a flower cluster. 

  • Having the radicle turned toward the sides of the fruit, as some embryos. 

noun
  • A rotating machine used to separate massecuite into sugar crystals and molasses. 

mysterious

adj
  • Difficult to understand. 

  • Having unknown qualities. 

  • Deliberately evasive or enigmatic. 

  • Of unknown origin. 

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