The meaning of FLUID is having particles that easily move and change their relative position without a separation of the mass and that easily yield to pressure : capable of flowing.
FLUID definition: a substance, as a 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 its shape. See examples of fluid used in a sentence.
FLUID definition: 1. a substance that flows and is not solid: 2. smooth and continuous: 3. If situations, ideas, or…. Learn more.
Fluids flow easily and take on the shape of their containers. All liquids and gases are fluids.
A situation that is fluid is unstable and is likely to change often. The situation is extremely fluid and it can be changing from day to day.
Most fluids are liquids or gases. Examples include air and water. A fluid is a material that flows or continuously deforms under a shear (tangential stress). In other words, a fluid has zero shear modulus. Liquids, gases, and plasma are fluids. However, some solids behave as fluids as well.
A fluid in medicine or biology refers to any liquid constituent of the body (body fluid), [6][7] whereas "liquid" is not used in this sense. Sometimes liquids given for fluid replacement, either by drinking or by injection, are also called fluids [8] (e.g. "drink plenty of fluids").
In contrast, liquids deform easily when stressed and do not spring back to their original shape once the force is removed because the atoms are free to slide about and change neighbors—that is, they flow (so they are a type of fluid), with the molecules held together by their mutual attraction.