允诺 (yǔn nuò) is a formal, written-style verb meaning 'to promise' or 'to pledge' — implying a serious, binding commitment, often made voluntarily and with sincerity. The first character 允 (yǔn) means 'to allow' or 'to consent', while the second, 诺 (nuò), means 'a promise' or 'an assurance'; together, they emphasize both permission to commit and the act of vowing. It appears frequently in official documents, literature, speeches, and solemn interpersonal contexts — such as making vows in relationships, signing agreements, or pledging support for a cause.

Unlike colloquial alternatives like 答应 (dā yìng), 允诺 carries weight and moral gravity; it suggests the speaker accepts responsibility for fulfilling the promise. It is rarely used in casual speech and almost never in commands or questions — instead, it appears in declarative statements describing completed or intentional commitments. Its tone is respectful and dignified, making it suitable for expressing trustworthiness, integrity, or earnest intention.