The antonyms for the word "most caved-in" can be "most intact", "most sturdy", "most stable", or "most unyielding". These antonyms indicate strength, durability, and resistance to collapse or damage. When something is "most intact", it has not suffered any breakage or deterioration, and is in its original form. Similarly, when something is "most sturdy" or "most stable", it can withstand pressure, weight, or force without giving in or collapsing. On the other hand, when something is "most caved-in", it suggests weakness, vulnerability, or destruction, and can be easily damaged or collapsed. Therefore, the antonyms for this word highlight the opposite qualities of strength and stability.