rocky vs unsound

rocky

adj
  • Like a rock; rigid, solid. 

  • In the style of rock music. 

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

  • Having a habitat around or on rocks. 

  • Easily rocked; unstable. 

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

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

unsound

adj
  • Not whole, not solid, defective. 

  • Infirm, diseased. 

  • Not good, unreliable. 

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