embolus vs infarction

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. 

infarction

noun
  • The process which causes an infarct. 

  • An infarct (an area of ischemic necrosis). 

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