To the letter is a phrase that means to follow something exactly or precisely. There are many synonyms for this phrase, including word for word, precisely, accurately, exactly, meticulously, thoroughly, rigorously, faithfully, conscientiously, and punctiliously. All of these words convey the idea of being extremely precise and adhering to the exact instructions or guidelines given. Whether you're trying to follow a recipe, a set of directions, or a formal decree, it's important to understand the concept of following something "to the letter". Using precise language and adhering to guidelines can help ensure that you achieve the desired outcome.