‘反悔’ (fǎn huǐ) is a verb meaning 'to go back on one's word' or 'to renege on a promise, agreement, or decision.' Literally, 反 (fǎn) means 'to reverse' or 'to oppose,' and 悔 (huǐ) means 'to regret.' Together, they express the act of reversing a prior commitment due to regret or changed circumstances. It implies a breach of trust or reliability and carries a slightly negative connotation—people who 反悔 are often seen as unreliable or indecisive.

This word is commonly used in interpersonal contexts: making promises, signing contracts, agreeing to plans, or even childhood pledges. It appears frequently in spoken Mandarin and informal writing, but is also appropriate in formal discussions about commitments. Unlike neutral terms like ‘改变主意’ (to change one’s mind), 反悔 emphasizes the moral weight of breaking a prior assurance—not just shifting preference, but violating an implicit or explicit obligation.