happening vs improbability

happening

adj
  • Trendy, up-to-the-minute. 

  • Busy, lively; vibrant, dynamic; fashionable. 

noun
  • Something that happens. 

  • A spontaneous or improvised event, especially one that involves audience participation. 

improbability

noun
  • The quality or state of being improbable; unlikelihood. 

  • That which is improbable; an improbable event or result. 

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