A formal pledge, bond, or legal guarantee; in Roman law, a security or undertaking given as a pledge.
From Latin cautio (caution, care, security). Related to cavere (to beware, take care), the same root giving us 'caution.' Used in legal Latin terms.
This legal term survives mainly in Latin phrases like 'cautio criminalis'—it shows how the Romans had formal procedures for people to pledge themselves as security. Medieval law courts inherited these exact procedures.
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