tornado vs waterspout

tornado

noun
  • A violent windstorm characterized by a mobile, twisting, funnel-shaped cloud. 

waterspout

noun
  • A whirlwind that forms over water, not associated with a mesocyclone of a thunderstorm (contrary to a true tornado). 

  • A plume of water rising from the surface of a body of water as the result of an impact or explosion. 

  • A true tornado that passes over a body of water. 

  • A channel through which water is discharged, especially from the gutters of a roof. 

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