The word "most unadvisable" means something that is not recommended or advisable. Its antonyms are words that indicate that something is wise, prudent, or recommended. Some of these antonyms are "sensible," "wise," "prudent," "judicious," "appropriate," "suitable," "advisable," and "sage." These words suggest that a course of action is well-considered, thoughtful, and smart. When someone or something is described by one of these antonyms, it suggests that they can be trusted to make the right decisions, or that their actions are appropriate and well thought out. The opposite of "most unadvisable," therefore, is a decision or action that is wise, thoughtful, and prudent.