The antonyms for the word "unwritten" can be a plethora of options. Some of the common antonyms include "written," "documented," "recorded," "published," "official," "established," and "formalized." Each of these words carries a different connotation and meaning, which could denote an opposite in the context of the usage. For instance, "written" and "documented" could signify that something has been put in writing, whereas "unwritten" implies that it has not. Similarly, "official" and "formalized" could indicate that something has been approved or recognized, while "unwritten" indicates that it hasn't. Ultimately, the choice of antonym depends on the specific context and intended meaning.