确定 (què dìng) means 'certain, confirmed' as an adjective, and 'to confirm, determine' as a verb. Unlike 确认 (què rèn) which is only a verb meaning 'to verify', 确定 can also describe a state of certainty. As an adjective it overlaps with 一定 and 肯定, but 一定 is more common as an adverb ('surely'), and 肯定 is typically used for subjective assurance ('definitely').