The opposite of in-exactness is precision. When something is precise, it is accurately measured or defined. Other antonyms for in-exactness include accuracy, exactness, and correctness. These words denote that something is without error or fault, and that it is not approximate or uncertain. Similarly, the antonym can also be termed as exactitude, which refers to the precision of exactness. Another possible antonym for in-exactness can be consistency, which means that something is reliable and constant, and that it is not subject to deviation or error. Overall, there are numerous antonyms for in-exactness that convey the opposite of vagueness and uncertainty.