descending vs drop-off

descending

noun
  • A descent. 

adj
  • Ordered such that each element is less than or equal to the previous element. 

  • Moving or sloping downwards. 

  • Becoming lower in pitch. 

  • Causing a sequence to follow a descending order. 

drop-off

noun
  • A sudden downward slope. 

  • A delivery; the act of leaving a package, etc. 

  • A visitor to a website who ceases to continue using and navigating around the site after reaching some specified page; or such an act of cessation. 

  • The precipitous outer side of a coral reef, facing the open sea. 

  • A sudden decrease. 

  • A space reserved outside a bus or railway station for vehicles stopping to drop off passengers for onward transit. 

  • A time during which passengers, such as school children, are dropped off. 

How often have the words descending and drop-off occurred in a corpus of books? (source: Google Ngram Viewer )