countersign

/ˈkaʊntərˌsaɪn/
verb
  1. To sign a document that has already been signed by someone else, in order to confirm its validity.
    • Please countersign the check to authorize the payment.
    • The manager needs to countersign the contract before it becomes official.
    • Both parents must countersign the permission slip for the field trip.
noun
  1. A secret signal or password used to confirm identity, especially in military or security contexts.
    • The spy whispered the countersign to gain entry to the safe house.
    • They agreed on a countersign to recognize each other in the dark.
    • The guard asked for the countersign before allowing the soldier through the gate.
Synonyms
What does "countersign" mean? | whatsthatwordmean | whatsthatwordmean