jettison vs offloading

jettison

noun
  • The action of jettisoning items. 

  • Items that have been or are about to be ejected from a boat or balloon. 

verb
  • To eject from a boat, submarine, aircraft, spaceship or hot-air balloon, so as to lighten the load. 

  • To let go or get rid of as being useless or defective. 

offloading

noun
  • The act by which something is offloaded. 

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