The antonyms for the word "nonstationary" are numerous and can be categorized into different contexts. First, in a scientific context, the antonyms include stationary, steady, stable, and constant. These terms describe a system or phenomenon that is unchanging or at rest. Second, in a personal context, the antonyms can include settled, established, predictable, and routine. These words reflect a sense of stability and consistency, indicating a lack of unpredictable change or movement. Third, in a technical context, the antonyms can include fixed, anchored, immobile, and static, which describe objects or systems that are not in motion or moving. Regardless of the context, the antonyms of nonstationary convey a sense of stability and predictability.