/ˌɛksprəʊˈmɪsə/ – noun
Definition: người gánh trách nhiệm của người khác, người gánh nợ của người khác.
A more thorough explanation: Expromissor is a legal term that refers to a person who makes a promise or undertakes an obligation without being requested or required to do so by another party. In other words, an expromissor voluntarily assumes a duty or obligation without any prior agreement or legal obligation to do so.
Example: The expromissor signed the contract, assuming the obligations of the original promissor.