depend vs snorkel

depend

verb
  • To hang down; to be sustained by being fastened or attached to something above. 

  • To trust; to have confidence; to rely. 

  • To cause to be contingent or dependent on; to set as a necessity. 

  • To be contingent or conditioned; to have something as a necessary condition; to hinge on. 

snorkel

verb
  • To use a snorkel. 

noun
  • A snorkel parka. 

  • A retractable tube fitted in diesel-engine submarines to allow sufficient ventilation that the engines may be used at periscope depth. 

  • A hollow tube, held in the mouth, or mounted on and opening into a diving mask, used by swimmers for breathing underwater. 

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