borderline vs line of demarcation

borderline

verb
  • To border, or border on; to be physically close or conceptually akin to. 

adj
  • Showing bad taste. 

  • Nearly; not clearly on one side or the other of a border or boundary, ambiguous. 

  • Exhibiting borderline personality disorder. 

adv
  • Nearly; not entirely but nevertheless to a great extent. 

noun
  • A boundary or accepted division; a border. 

  • An individual who has borderline personality disorder. 

line of demarcation

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