The word "un-permissible" means something that is not allowed or prohibited. Some common antonyms for "un-permissible" include "permissible," "allowed," "acceptable," "legal," "lawful," and "approved." When something is "permissible," it means that it is allowed and within the limits of what is considered acceptable. This word is often used in a legal or official context. For example, certain behaviors and actions may be deemed un-permissible in public places, but they can become permissible under certain conditions. Antonyms for "un-permissible" can refer to something that is authorized, legitimate, or sanctioned in a particular situation.