polyp vs polypus

polyp

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

  • An abnormal growth protruding from a mucous membrane. 

polypus

noun
  • A cardiac thrombus usually found post-mortem. 

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