悔改 (huǐ gǎi) is a compound verb meaning 'to repent and reform' — it expresses both sincere regret for past wrongdoing and a committed effort to change one’s behavior. The first character, 悔 (huǐ), means 'to feel remorse or regret', often with emotional weight and moral awareness; the second, 改 (gǎi), means 'to change or correct', emphasizing concrete action. Together, they convey a holistic transformation: not just feeling sorry, but actively turning away from error and adopting better conduct.

This word is commonly used in religious, ethical, legal, or educational contexts — especially when discussing moral growth, personal accountability, or societal rehabilitation. It carries a formal and serious tone, implying depth of reflection and seriousness of intent. While it can appear in everyday speech about personal growth, it is more frequent in written language, sermons, official statements, or literature dealing with redemption and self-improvement.