irritability vs moodiness

irritability

noun
  • The state or quality of being irritable; quick excitability 

  • A natural susceptibility, characteristic of all living organisms, tissues, and cells, to the influence of certain stimuli, response being manifested in a variety of ways. 

  • A condition of morbid excitability of an organ or part of the body; undue susceptibility to the influence of stimuli. 

moodiness

noun
  • The property of being moody. 

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