countersign

Meaning

noun

1. a secret word or phrase known only to a restricted group
   “he forgot the password”
2. a second confirming signature endorsing a document already signed

verb

1. add one's signature to after another's to attest authenticity
   “You must countersign on this line of the contract”

Synonyms for countersign

• password
• watchword
• word
• parole
• countersignature