A person who pledges themselves or their property as a guarantee for someone else's debt; a guarantor or surety.
From Latin 'fideiussor' (one who guarantees in good faith), from 'fidei' (of faith) and 'iussor' (one who orders or binds). Central to Roman contract law.
Being a fidejussor in ancient Rome was serious business—you could literally be enslaved if the person you vouched for didn't pay their debts, making personal reputation worth as much as money.
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