The word "unerroneous" refers to something that is without error or fault. Synonyms for this word could include accurate, correct, precise, flawless, faultless, immaculate, or unblemished. These words describe the state of being perfect or free from mistakes, and are often used in the context of scientific or mathematical accuracy, as well as general descriptions of processes or results that are without any flaws or inaccuracies. Using these synonyms can help to add variety and depth to your writing, while also emphasizing the importance of accuracy and precision in any context where they are necessary.