Civil Law. Also 8 expromissar. [a. L. exprōmissor, agent-n. f. exprōmittĕre to promise to pay, f. ex- (see EX- pref.1) + prōmittĕre to PROMISE.] One who promises to pay; spec. one who unconditionally undertakes the debt of another, so as to become the principal debtor in his stead; distinguished from a ‘surety’ or ‘bail.’
1695. S. Lobb, Lett. to Dr. Bates, 12. You distinguish between the Covenant of Grace, and the Covenant of Redemption, and grant Christ to be a Surety in the One and an Expromissor in the other.
1775. Ash, Expromissar.
1818. Colebrooke, Treat. Obligations & Contracts, I. 211. The ex-promissor, who is to undertake the debt.
1875. Poste, Gaius, III. Comm. (ed. 2), 406. A woman does not, like an Expromissor, discharge a pre-existing obligation.
