歉疚 is a formal, literary noun meaning deep remorse or guilt—stronger than ordinary regret. It combines 歉 (qiàn), which conveys apology or apology-related feelings, and 疚 (jiù), which means inner pain or moral anguish caused by wrongdoing. Together, they express a profound, self-directed emotional burden arising from having harmed others, broken trust, or failed in duty.

This word appears frequently in reflective writing, literature, and serious spoken contexts—such as apologies, confessions, or moral self-evaluation. It’s rarely used in casual speech; learners should avoid overusing it in everyday conversation, where simpler terms like 内疚 (nèi jiù) or 愧疚 (kuì jiù) are more common. 歉疚 carries a tone of solemn responsibility and often implies the speaker acknowledges personal fault and feels unworthy of forgiveness.