inconsistency vs irregularity

inconsistency

noun
  • The state of being inconsistent. 

  • An incompatibility between two propositions that cannot both be true. 

irregularity

noun
  • An instance of being irregular. 

  • A violation of rules. 

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

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

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

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