centrifugal vs unstable

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. 

unstable

adj
  • Fluctuating; not constant. 

  • Readily decomposable. 

  • Not stable. 

  • Radioactive, especially with a short half-life. 

  • Unpredictable. 

  • Fickle. 

  • Having a strong tendency to change. 

verb
  • To release (an animal) from a stable. 

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