changeable vs rocky

changeable

adj
  • Subject to sudden or frequent changes. 

  • Capable of being changed. 

  • Capable of camouflaging itself by changing colour. 

rocky

adj
  • Encountering many problems; difficult, troubled; also, in danger or distress. 

  • In the style of rock music. 

  • Abounding in, or full of, rocks; consisting of rocks. 

  • Like a rock; rigid, solid. 

  • Having a habitat around or on rocks. 

  • Easily rocked; unstable. 

  • Of a person: ill, or unsteady (for example, as a result of a shock). 

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