Un-soundness refers to a lack of stability, solidity, or reliability. Its antonyms include terms such as soundness, stability, reliability, and robustness. Soundness presents a level of safety and confidence in the value of an entity, while stability refers to a consistent and steady state of being. Some related antonyms of un-soundness include healthiness, strength, and resilience, which imply a capacity for growth, adaptability, and recovery from a setback. In contrast, fragility or weakness can be considered antonyms of soundness, as they suggest a susceptibility to harm or damage. In short, antonyms of un-soundness portray the opposite of its meaning, representing everything that is firm, dependable, and enduring.