The phrase "letter-perfection" refers to something that is flawless or precise in written form. Some synonyms for this term include "impeccable," "flawless," "excellent," "precise," "accurate," "exact," "faultless," "spotless," "unblemished," "unimpaired," and "unblemished." Each of these terms relates to a level of perfection in writing or literature, where every word is chosen and used with care and the final product is without error or fault. Whether you are writing a book, a letter, or a simple text message, it is important to strive for letter-perfection to ensure your message is communicated accurately and clearly.