irruption vs outbreak

irruption

noun
  • An abrupt increase in the size of a movement or organization. 

  • An abrupt increase of an animal population. 

  • The action of irrupting or breaking into; a violent entry or invasion; an inbreaking; an intrusion. 

outbreak

noun
  • A sudden increase. 

  • An eruption; the sudden appearance of a rash, disease, etc. 

  • Synonym of breakout (“escape from prison”) 

  • An outburst or sudden eruption, especially of violence and mischief. 

verb
  • To burst out or break forth. 

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