›one of two or more people, countries or organizations who sign an official agreement or document: He is a cosignatory to a letter, published in the Financial Times.Canada is a co-signatory of the North American Free Trade Agreement.
›a person or organization that signs a document already signed by another person, agreeing to pay that person’s debt if they fail to do so: British students in the US need a local co-signatory to apply for a loan.
›one of two or more people or organizations who take equal responsibility for a financial arrangement: When one of the co-signatories dies, all of the assets in the joint bank account will continue to be available to their partner.As a co-signatory to the mortgage, she is considered a joint investor in the fund.