肯定 (kěn dìng) is a versatile word meaning 'certainly', 'definitely', or 'affirmative'. It combines 肯 (kěn), which conveys willingness or readiness, and 定 (dìng), meaning 'to settle', 'to decide', or 'fixed'. Together, they express firm conviction or unambiguous agreement — as if something has been settled with confidence. It’s commonly used to emphasize certainty in statements, confirm information, or respond affirmatively to questions.

The word functions both as an adverb (modifying verbs or whole sentences, e.g., 我肯定去) and as a verb meaning 'to affirm' or 'to confirm' (e.g., 他肯定了这个方案). It appears frequently in spoken and written Chinese across contexts — from casual conversation ('Yes, definitely!') to formal reports ('The data confirms the hypothesis'). Its tone is neutral and widely appropriate, though overuse in formal writing can sound imprecise compared to more specific terms like 确实 or 确认.