Skip to definition.  Noun: countersign  'kawn-tu(r),sIn   1. A
secret word or phrase known only to a restricted group     "he
forgot the countersign";     - password, watchword, word, parole
2. A second confirming signature endorsing a document already
signed     - countersignature Verb: countersign  'kawn-tu(r),sIn
1. Add one's signature to after another's to attest authenticity
"You must countersign on this line of the contract"  Derived
forms: countersigned, countersigning, countersigns  Type of:
arcanum, positive identification, secret, sign, signature
Encyclopedia: Countersign