nonregularity vs randomness

nonregularity

noun
  • The state or condition of being nonregular. 

randomness

noun
  • A measure of the lack of purpose, logic, or objectivity of an event. 

  • The property of all possible outcomes being equally likely. 

  • A type of circumstance or event that is described by a probability distribution. 

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