后悔 (hòu huǐ) is a verb meaning 'to regret' — to feel sorrow or disappointment about something one has done or failed to do. The character 后 (hòu) means 'after' or 'later', and 悔 (huǐ) means 'to feel remorse' or 'to repent'. Together, they literally convey the idea of 'feeling remorse after an action has occurred', emphasizing that regret arises only in hindsight. It's commonly used to express personal responsibility for past choices, especially decisions with negative consequences.

This word carries emotional weight and is often used in reflective, serious, or confessional contexts — such as apologizing, reflecting on life choices, or warning others based on one’s own experience. It can be used both transitively (e.g., 后悔做某事 — 'regret doing something') and intransitively (e.g., 我很后悔 — 'I deeply regret'). Unlike casual expressions like 遗憾 (yíhàn, 'regret/disappointment'), 后悔 implies a stronger sense of self-blame and personal agency.