spon·​sion | \ ˈspänchən\
plural -s

Definition of sponsion

1 Roman law : suretyship accessory to oral contracts and available only to Roman citizens
2 : the act of becoming surety especially : a formal pledge made on behalf of another
3 : an act or engagement on behalf of a state undertaken by an agent not specially authorized or by one who exceeds the limits of his authority and requiring for validity ratification by the state

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History and Etymology for sponsion

Latin sponsion-, sponsio, literally, solemn promise, pledge, from sponsus (past participle of spondēre to promise solemnly) + -ion-, -io -ion

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