deadline vs hard stop

deadline

noun
  • A time limit in the form of a date on or before which something must be completed. 

verb
  • To render an item non-mission-capable; to ground an aircraft, etc. 

hard stop

noun
  • A definite time when someone must end a task in order to meet another time commitment. 

  • A mechanical device that limits the travel of a mechanism. 

  • A tactic used by armed police to stop a vehicle believed to contain dangerous criminals. 

  • Synonym of full stop 

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