"Most stiffened" implies rigid or hardened, suggesting a lack of flexibility or malleability. Its antonyms could include words such as flexible, pliable, supple, bendable, or adaptable. These words convey the opposite meaning, describing something that can be shaped or molded, able to adjust to changing circumstances. These antonyms suggest fluidity, versatility and resilience, qualities that are useful in many situations, from physical objects to human attitudes and behaviors. By considering the antonyms for "most stiffened," we can expand our vocabulary, develop a more nuanced understanding of language, and learn to express ourselves more precisely and effectively.