irregularity vs singularity

irregularity

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

  • 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). 

singularity

noun
  • The state of being singular, distinct, peculiar, uncommon or unusual. 

  • An unusual action or behaviour. 

  • A point where all parallel lines meet. 

  • Celibacy, singleness (as contrasted with marriage). 

  • A point where a measured variable reaches unmeasurable or infinite value. 

  • The value or range of values of a function for which a derivative does not exist. 

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