More unpermissible means something that is even more unacceptable or prohibited. Its antonyms would be words that indicate something that is acceptable or permissible. For example, the word 'permissible' means allowed or acceptable, so its antonyms would be disallowed or prohibited. Other antonyms for more unpermissible include acceptable, lawful, legal, legitimate, permitted, sanctioned, and allowable. These words describe actions or behaviors that are allowed or approved of by society, law, or authority. It is important to understand the opposite or antonyms of a word to use it properly in a sentence and to communicate effectively.