alteration vs instability

alteration

noun
  • The state of being altered; a change made in the form or nature of a thing; a changed condition. 

  • The act of altering or making different. 

instability

noun
  • A state that is not in equilibrium, or in which a small change has a large irreversible effect. 

  • The quality of being unstable. 

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