- cosigner, cosignatory - one of two or more signers of the same document (as a treaty or declaration)
--1 is a kind of signer, signatory
Derived form: verb cosign1 - cosigner - a signer in addition to the principal signer (to verify the authenticity of the principal signature or to provide surety)
--2 is a kind of signer, signatory
Derived form: verb cosign2