cachet vs letterhead

cachet

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

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

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

  • A capsule containing a pharmaceutical preparation. 

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

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

letterhead

noun
  • Paper marked with a letterhead. 

  • A portion of text at the top of a letter, identifying the sender and often giving their address etc., used for formal correspondence. 

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