The term "most transformable" corresponds to an object or idea that can undergo extensive alterations. Its antonyms, therefore, refer to words that exhibit durability and resistance to changes. These synonyms include unchangeable, fixed, immutable, perpetual, stagnant, and stubborn. For instance, an object that is rigid and unchanging can be described as immutable or fixed. On the other hand, a person who is resistant to change, whether it's blocking out new ideas or remaining steadfast in existing beliefs, can be described as stubborn, stagnant and unyielding. Although some of these antonyms may have negative connotations, they describe the opposite of the versatility or evolvability implied by the term "most transformable.