cosign

1. To sign (a document) jointly.
2. To endorse (another's signature), as for a loan.

The act of signing for another person's debt which involves a legal obligation made by the cosigner to make payment on the other person's debt should that person default. Having a cosigner is way for individuals with a low income or poor/limited credit history to obtain financing.

This term is also commonly spelled "co-sign".

Investopedia Says:
A cosigner's obligation to repay debt arises only after the borrower has defaulted on the loan; however, cosigning a loan is not without risk. A person cosigning a loan should be comfortable with the borrower's ability to repay the debt.

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Act of affixing one's signature on a contract, such as a loan, in addition to the principal signature of another. Both signers are liable for the loan or other contract.

An obligor — a person who becomes obligated, under a commercial paper, such as a promissory note or check — by signing the instrument in conjunction with the original obligor, thereby promising to pay it in full.

The cosigner may be held equally responsible for the payment of the debt or may be required to pay only upon the failure of the original obligor to do so, depending upon state law and the terms of the agreement that also determine the rights of the cosigner.

Cosigner is synonymous with the term comaker.

Tutor's tip: To "consign" is to transfer or give to another's care or control, to "cosign" is to sign a loan agreement with others, while "cosine" is a mathematical term used in trigonometry.