crash pad vs walk-up

crash pad

noun
  • A place of temporary lodging for airline flight crews. 

  • A room where one can recover after a bad acid trip. 

  • A protective foam pad placed on the ground, used as protection in case of falling from the wall. 

  • Any place used for temporary lodging, especially without payment or permission. 

walk-up

noun
  • An informal visit to a control tower by a pilot, typically used as part of pilot training. 

  • An indoor or outdoor stand where food is sold to the public. 

  • An apartment or block with stairs rather than an elevator. 

  • A customer who arrives without a reservation; a walk-in. 

  • A mountain that can be climbed without specialist equipment. 

  • Colaptes auratus, northern flicker. 

adj
  • For which no appointment is necessary. 

  • Containing such flats. 

  • Reached by stairs rather than an elevator. 

How often have the words crash pad and walk-up occurred in a corpus of books? (source: Google Ngram Viewer )