The word "moldiest" refers to something that is covered in mold, mildew, or fungal growth. However, there are several synonyms for this word that can be used to add variety to your writing. For instance, you can use the word "mustiest" to describe something that has an unpleasant smell due to being damp and stale. Similarly, you could use the term "fungoid" to describe something that is moldy or mushroom-like. Another alternative to "moldiest" is "decaying," which implies a sense of rot and decomposition. Ultimately, choosing the right synonym for "moldiest" depends on the specific context of your writing and the mood you want to convey.