The noun fluid has 2 senses (first 2 from tagged texts)
1. (26) fluid -- (a substance that is fluid at room temperature and pressure)
2. (8) fluid -- (a continuous amorphous substance that tends to flow and to conform to the outline of its container: a liquid or a gas)
Overview of adj fluid
The adj fluid has 5 senses (first 1 from tagged texts)
1. (1) fluid, unstable -- (subject to change; variable; "a fluid situation fraught with uncertainty"; "everything was unstable following the coup")
2. fluid, runny -- (characteristic of a fluid; capable of flowing and easily changing shape)
3. 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")
4. fluid, liquid -- (in cash or easily convertible to cash; "liquid (or fluid) assets")
5. fluid, mobile -- (affording change (especially in social status); "Britain is not a truly fluid society"; "upwardly mobile")