countersign vs endorse

countersign

verb
  • To add a second signature to a document, affirming the validity of the signature of another person. 

  • To sign on the opposite side of (a document). 

noun
  • A second signature added to a document to affirm the validity of the signature of the first person. 

  • The response to a sign or signal. 

endorse

verb
  • To write one's signature on the back of a cheque, or other negotiable instrument, when transferring it to a third party, or cashing it. 

  • To report (a symptom); to describe. 

  • To express support or approval, especially officially or publicly. 

  • To give an endorsement. 

noun
  • A diminutive of the pale, usually appearing in pairs on either side of a pale. 

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