Antonyms for the word "most distensible" include words that denote stiffness, rigidity, and inflexibility. Such antonyms include "inflexible," "rigid," "stiff," "immovable," and "unyielding." These words describe objects that are not easily stretched or expanded, or that resist any type of deformation or change. In contrast to the malleability and elasticity implied by "most distensible," these words suggest a lack of adaptability and responsiveness. Other antonyms for "most distensible" could also include words such as "unchangeable," "fixed," "stubborn," and "intransigent," which all denote a reluctance to modify or transform under any circumstances.