cachet vs tuberculum

cachet

noun
  • A capsule containing a pharmaceutical preparation. 

  • A special characteristic or quality; prestige, especially via association. 

  • A sealed envelope containing an item whose price is being negotiated. 

  • A commemorative stamped design or inscription on an envelope, other than a cancellation or pre-printed postage. 

  • A hidden location from which one can observe birds while remaining unseen. 

verb
  • To mark (an envelope) with a commemorative stamped design or inscription. 

tuberculum

noun
  • tubercle 

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