The phrase "most rattleboned" can be used to describe something that is extremely fragile or weak. Some antonyms for this phrase could be strong, sturdy, robust, durable, resilient, and tough. These words describe objects or materials that can withstand stress, pressure, or damage without breaking or falling apart. In contrast, fragile or weak items are vulnerable to breaking or falling apart under pressure, which could be exemplified by antonyms like frail, delicate, brittle, or feeble. Antonyms for "most rattleboned" can be used to describe anything from a crumbling building to a fragile piece of porcelain.