retirement vs undisturbed area

retirement

noun
  • An act of retiring; withdrawal. 

  • The state of being retired; seclusion. 

  • The state of having permanently left one's employment, now especially at reaching pensionable age; the portion of one's life after retiring from one's career. 

  • The act of leaving one's career or employment permanently. 

undisturbed area

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