fluid >> ˈfluːɪd
Definition: [noun] a substance that has no fixed shape and yields easily to external pressure; a gas or (especially) a liquid.
Example: body fluids
Definition: [adjective] (of a substance) able to flow easily.
Example: the paint is more fluid than tube watercolours
Definition: [adjective] (of a clutch or coupling) using a liquid to transmit power.