definition of
fluid

[1] #1 fluid n. a substance that is fluid at room temperature and pressure. wn

[2] #2 fluid s. [unstable] subject to change; variable; "a fluid situation fraught with uncertainty"; "everything was unstable following the coup". wn

[3] #3 fluid n. continuous amorphous matter that tends to flow and to conform to the outline of its container: a liquid or a gas. wn

[4] #4 fluid s. [runny] characteristic of a fluid; capable of flowing and easily changing shape. wn

[5] #5 fluid s. [fluent, liquid, smooth] smooth and unconstrained in movement; "a long, smooth stride"; "the fluid motion of a cat"; "the liquid grace of a ballerina". wn