Part of speech: Verb
add one's signature to after another's to attest authenticity
Example: You must countersign on this line of the contract
Categories: Sign
The word "countersign" comes from Middle French contresigne.
counter – A related word in the same word family.
sign – A related word in the same word family.
For 300 years after 1066, French was the language of English courts and nobility.