The antonyms for the word "most unstationary" would be words that indicate stability and a lack of movement. Some antonyms that come to mind include rooted, permanent, stable, stationary, motionless, fixed, and immobile. These words suggest a sense of stillness and permanence, signaling the opposite of what "most unstationary" implies. These antonyms can be used in various contexts such as describing objects, situations, or even people's personalities. By using these antonyms, you can convey a different message and emphasize qualities such as steadiness, reliability, and constancy, which can be valued in different situations.