Passcode and Countersign

noun

• A secret word or phrase known only to a restricted group.
  • usage: "he forgot the password"
  • synonyms: password, watchword, word, parole
• A second confirming signature endorsing a document already signed.
  • synonyms: countersignature

verb

• Add one's signature to after another's to attest authenticity.
  • usage: "You must countersign on this line of the contract"

• (a.) A private signal, word or phrase, which must be given in order to pass a sentry; a watchword.
• (a.) The signature of a secretary or other officer to a writing signed by a principal or superior, to attest its authenticity.
• (v.t.) To sign on the opposite side of (an instrument or writing); hence, to sign in addition to the signature of a principal or superior, in order to attest the authenticity of a writing.