不惭 is a classical Chinese adjective meaning 'unashamed' or 'unrepentant', describing someone who feels no shame or remorse about their actions, words, or status—even when others might expect them to. The character 不 (bù) is a negation prefix, and 惭 (cán) means 'to feel ashamed' or 'to feel remorse', derived from the heart radical and suggesting an internal emotional response. Together, they form a compact, literary expression emphasizing moral or social imperviousness to shame.

This term appears primarily in classical texts, historical narratives, and formal or rhetorical contexts—not in everyday spoken Mandarin. It often carries a subtle evaluative tone: sometimes neutral (e.g., unashamed of humble origins), sometimes critical (e.g., unrepentant after wrongdoing). Modern speakers rarely use it conversationally; instead, they prefer phrases like 毫不惭愧 (háo bù cánkuì) or 无耻 (wúchǐ) for stronger disapproval. Its brevity and elegance make it favored in idioms, poetry, and scholarly writing.