drop-off vs upgrade

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. 

upgrade

noun
  • An upward grade or slope. 

  • An improvement 

  • An improved component or replacement item, usually applied to technology 

verb
  • To improve, usually applied to technology, generally by complete replacement of one or more components 

  • To replace with something better. 

  • To improve the equipment or furnishings of or services rendered to 

  • To replace a program with a later version of itself, a version having a higher version number or marketed under a more recent product name. 

  • To improve in condition or status. 

adv
  • Up a slope or grade. 

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