A person who signs a legal document alongside another person, agreeing to share the financial or legal responsibilities.
From co- (together) + signer (one who signs). Popularized in American English during the 20th century, especially in banking and credit industries.
Cosigners are financial safety nets for lenders—if you can't pay a loan, the cosigner's credit gets damaged too, so most people only ask family members they trust deeply.
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