brevet vs countersignature

brevet

noun
  • An authoritative grant or mark of recognition; a seal of approval. 

  • An organized, long-distance bicycle ride — not a race, but a test of endurance — which follows a designated but unmarked route passing through check points. 

  • A warrant from the government, granting a privilege, title, or dignity, as in France. 

  • A military document entitling a commissioned officer to hold a higher rank temporarily, but without an increase in pay. 

verb
  • To promote by brevet. 

countersignature

noun
  • A signature made to confirm or endorse another. 

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