irregularity vs stability

irregularity

noun
  • A violation of rules. 

  • An object or event that is not regular or ordinary. 

  • An instance of being irregular. 

  • Irregular bowel movement (e.g. diarrhea or constipation). 

  • The state or condition of being irregular, or the extent to which something is irregular. 

stability

noun
  • The condition of being stable or in equilibrium, and thus resistant to change. 

  • The tendency to recover from perturbations. 

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