deboard vs unload

deboard

verb
  • To exit a form of transportation such as a boat, ship, airplane, trolley, streetcar or spaceship. 

unload

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

  • 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 get rid of or dispose of. 

  • 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 deboard and unload occurred in a corpus of books? (source: Google Ngram Viewer )