jettison vs unload

jettison

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

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

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

  • The action of jettisoning items. 

unload

verb
  • To get rid of or dispose of. 

  • To reduce the vertical load factor on (an airplane's wing or other lifting surface), typically by pitching downwards toward the ground to decrease angle of attack and reduce the amount of lift generated. 

  • To remove (the load or cargo) from a vehicle, etc. 

  • To deposit one's load or cargo. 

  • To give vent to or express; to unburden oneself of. 

  • To discharge, pour, or expel. 

  • To remove the load or cargo from (a vehicle, etc.). 

  • To remove the charge from. 

  • To deliver forcefully. 

  • To ejaculate, particularly within an orifice. 

  • To remove (something previously loaded) from memory. 

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