The term "most irrefrangible" refers to something that is extremely difficult to break or change, making it almost impossible to refute or deny. Its antonyms would include words such as malleable, flexible, pliable, supple, and yielding. These words imply that the subject is easy to shape, mold or manipulate, making it susceptible to change or influence. If something is not irrefrangible, it means that it is subject to alteration, which makes it less rigid and more adaptable. While irrefrangibility can be a desirable characteristic in some contexts, it is not always the most suitable for all situations.