S: (adj) fluid, unstable (subject to change; variable) "a fluid situation fraught with uncertainty"; "everything was unstable following the coup"
S: (adj) fluid, runny (characteristic of a fluid; capable of flowing and easily changing shape)
S: (adj) fluent, fluid, liquid, smooth (smooth and unconstrained in movement) "a long, smooth stride"; "the fluid motion of a cat"; "the liquid grace of a ballerina"
S: (adj) changeable, changeful (such that alteration is possible; having a marked tendency to change) "changeable behavior"; "changeable moods"; "changeable prices"