The word "un-wiser" can be difficult to find synonyms for, as it's not a commonly used word. However, some alternatives could include "less knowledgeable," "less experienced," "less mature," "less astute," or "less discerning." Each of these words expresses a similar idea: someone who is not as wise as they could be. The choice of synonym will depend on the context in which the word is used, as well as the tone desired by the writer or speaker. Regardless of the synonym chosen, the meaning will remain the same: someone who lacks wisdom or experience.