harpoon vs trident

harpoon

noun
  • A spearlike weapon with a barbed head used in hunting whales and large fish. 

  • A harmonica. 

verb
  • To shoot something with a harpoon. 

trident

noun
  • A three-pronged spear somewhat resembling a pitchfork. 

  • A curve of third order of the form 

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