The word "letter-perfect" means to be precise and accurate, indicating that something is without errors or mistakes. Antonyms for "letter-perfect" include words like flawed, incorrect, inaccurate, erroneous, imprecise, and faulty. When writing, it's important to avoid using just one set of words in your vocabulary. Antonyms can bring a lot of variety to your writings, making them more interesting and engaging to read. By using different antonyms, you can also emphasize the contrast between what is perfect and imperfect, which can be quite effective in making your point.