idiosyncrasy vs unpredictability

idiosyncrasy

noun
  • A peculiarity that serves to distinguish or identify. 

  • A peculiar individual reaction to a generally innocuous substance or factor. 

  • A language or behaviour that is particular to an individual or group. 

  • A behavior or way of thinking that is characteristic of a person. 

unpredictability

noun
  • Something which is unpredictable. 

  • The quality of being unpredictable. 

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