1. countersign - Noun
2. countersign - Adjective
3. countersign - Verb
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.
The signature of a secretary or other officer to a writing signed by a principal or superior, to attest its authenticity.
A private signal, word, or phrase, which must be given in order to pass a sentry; a watchword.
Source: Webster's dictionaryhe forgot the password Source: Internet
You must countersign on this line of the contract Source: Internet