The antonyms for the word "most caved in" are firm, strong, stable, robust, hard, solid, unyielding, tough, unbreakable, and sturdy. These words convey the opposite meaning of caved in, which implies weakness and fragility. When we describe something as firm, it indicates that it is rigid and unyielding, while sturdy suggests something that is well-built and can withstand pressure. Similarly, robust and strong describe something that is healthy and vigorous, while hard implies that something is difficult to break or bend. These antonyms can be used in different contexts to highlight the strength and resilience of an object or an individual.