Fluid

[1] A substance which flows, e.g., a liquid or a gas.
[2] Substance in either a liquid or gaseous state; substance containing particles which move and change position without separation of the mass.
[3] Any liquid or gas that is capable of flowing and that changes its shape at a steady rate when acted upon by a force tending to change it shape. A term used to refer to any substance having the above properties.
See also automatic transmission fluid, battery fluid, brake fluid, easing fluid, hydraulic fluid, releasing fluid, silicone brake fluid, transmission fluid, washer fluid, windshield washer fluid