embolus vs stoppage

embolus

noun
  • An obstruction causing an embolism: a blood clot, air bubble or other matter carried by the bloodstream and causing a blockage or occlusion of a blood vessel. 

  • The structure on the end of the palp of male arachnids which contains the opening to the ejaculatory duct. 

stoppage

noun
  • Something that forms an obstacle to continued activity; a blockage or obstruction. 

  • A pause or halt of some activity. 

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