The word "nonimmutable" means not unchangeable or not permanent. Therefore, its antonyms are synonyms of words like permanent, unchangeable, and enduring. The antonyms for "nonimmutable" include words such as immutable, fixed, enduring, permanent, stable, steadfast, changeless, invariable, and consistent. These words suggest ideas of things that are not subject to change, modification, or alteration. These words can help contrast the meaning of "nonimmutable" and create a clearer understanding of the concept of permanence or stability. When we relate these antonyms to "nonimmutable," we can emphasize the importance of preservation or stability in the context of a particular situation or concept.