Which term refers to something that is changeable?

The term that refers to something that is changeable is "Variable." In various contexts, a variable denotes an element that can undergo changes and fluctuations. In mathematics and science, for instance, variables represent quantities that can vary, depending on different conditions or inputs. This concept of variability is essential in experimentation and modeling, as it allows for the observation of how changes in one factor can influence another.

While the term "Concrete" suggests something that is definite and stable, "Static" indicates something that lacks movement or change. "Fleeting," on the other hand, relates to something that is temporary or transitory, but it doesn't capture the broader sense of variability as effectively as "Variable." Therefore, "Variable" is the most appropriate term to describe something that is inherently changeable.