Cosigner
Also called: co-signer, guarantor, co-borrower
A cosigner promises to repay a loan if the primary borrower doesn't, letting someone with thin or damaged credit qualify. The legal reality is harsher than the word suggests: the cosigner is fully liable from day one, the debt appears on their credit report and DTI, and the lender can pursue them without chasing the borrower first. Most agreements have no exit; releasing a cosigner usually requires refinancing the loan entirely.