不肯 (bù kěn) is a compound verb meaning 'refuse to' or 'be unwilling to'. It combines the negation particle 不 (bù), which means 'not', and 肯 (kěn), which means 'to be willing' or 'to consent'. Together, they express a firm, often emotional or stubborn, refusal — not just inability or lack of opportunity, but a deliberate choice not to comply. The word carries a sense of volition and resistance, frequently implying personal attitude, emotion, or character.

不肯 is commonly used with verbs in the complement position: e.g., 不肯去 (refuse to go), 不肯说 (refuse to speak), or 不肯吃 (refuse to eat). It often appears in contexts involving children, animals, or people expressing strong will — such as defiance, shyness, pride, or fear. Unlike 不要 (bù yào), which expresses preference or rejection of something, 不肯 emphasizes internal unwillingness to perform an action.