fluid (Noun) — A substance that is fluid at room temperature and pressure.
fluid (Noun) — Continuous amorphous matter that tends to flow and to conform to the outline of its container: a liquid or a gas.
fluid (Adjective) — Subject to change; variable. ex. "a fluid situation fraught with uncertainty"
fluid (Adjective) — Characteristic of a fluid; capable of flowing and easily changing shape.
fluid (Adjective) — Unconstrained and flowing smoothly in movement. ex. "the fluid motion of a cat"
fluid (Adjective) — In cash or easily convertible to cash. ex. "fluid assets"
fluid (Adjective) — Affording change (especially in social status). ex. "Britain is not a truly fluid society"