The word 许诺 is formed by combining two characters, 许 and 诺, which both individually carry the core meaning related to speaking an assurance. 许 means "to allow" or "to promise", while 诺 means "to assent" or "yes", historically used as a formal response to acknowledge a command or request. When joined, they create a compound where each character reinforces and deepens the other's meaning, merging the act of putting forth a promise (许) with the concept of explicit agreement or pledge (诺) to form the complete idea of "to make a promise" or "a pledge".