keep waiting vs loiter

keep waiting

loiter

verb
  • To remain at a certain place instead of moving on. 

  • To stand about without any aim or purpose; to stand about idly. 

  • For an aircraft to remain in the air near a target. 

noun
  • A standing or strolling about without any aim or purpose. 

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