The word "most softshelled" refers to something that is easily crushed or pierced, lacking in hardness or rigidity. The antonyms of this phrase may include words such as firm, solid, strong, tough, rigid, and hard-wearing. These words describe objects with durability and sturdiness, such as a diamond or a cast iron skillet. They convey the opposite of "most softshelled," meaning they are more resilient and less prone to breaking or getting damaged. These antonyms can be used to describe materials, objects, or even individuals who possess qualities such as strength, resilience, and unyielding perseverance.