More tumbledown is an adjective that describes something that is in a state of disrepair, dilapidation, or decay. Antonyms for this word include robust, sturdy, sound, secure, and well-maintained. A robust building, for instance, is one that is sturdy and strong, without any signs of weakness or fragility. A sturdy object, on the other hand, is one that is solidly constructed and able to withstand pressure and wear. A sound structure or item is one that is free from defects or damages, while a secure one is one that is firmly anchored and protected against intruders or damages. Finally, a well-maintained property or item is one that is regularly cared for and kept in good condition.