The word fluxional refers to something that is constantly changing or in a state of fluctuation. In order to express similar concepts, there are a variety of synonyms that can be used. Some of these include: mutable, variable, fluid, dynamic, unstable, mercurial, shifting, changing, transitional, and inconstant. Each of these words conveys a sense of movement and transformation, and can be used to describe anything from a changing landscape to a shifting mood or attitude. By using these synonyms instead of the word fluxional, you can add nuance and depth to your writing, while still conveying the same general idea.