embolus vs impediment

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. 

impediment

noun
  • Baggage, especially that of an army; impedimenta. 

  • A disability, especially one affecting the hearing or speech. 

  • A hindrance; that which impedes or obstructs progress. 

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