polyp vs protuberance

polyp

noun
  • An abnormal growth protruding from a mucous membrane. 

  • A cylindrical coelenterate, such as the hydra, having a mouth surrounded with tentacles. 

protuberance

noun
  • A bulge, knob, swelling, spine or anything that protrudes. 

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