Antonyms for the word "most stretchable" could be words such as inflexible, rigid, stiff, unyielding or inelastic. While most stretchable refers to an object's ability to expand and stretch, these antonyms indicate a lack of capability to stretch or adapt to changes. The opposite of stretching, these words describe objects that are resistant to movement, bending, or alteration. Other antonyms could include brittle, fragile, or delicate, which denote a tendency to break or snap easily. Within the context of fabrics and materials, these antonyms represent less desirable properties, as they can limit both comfort and durability.