What is the state of matter with definite volume but no definite shape? It is a liquid.
Liquid particles remain close enough together to give a liquid a nearly fixed volume, but they can move past one another. As a result, a liquid flows and takes the shape of its container rather than maintaining a rigid form like a solid.
Liquids are generally much less compressible than gases because their particles are already packed relatively closely. Their behavior also depends on temperature and pressure: heating can cause a liquid to evaporate or boil, while cooling can make it freeze into a solid.
A frequent confusion is to say that liquids have “no volume.” They do have a definite volume under ordinary conditions; it is their shape that is not fixed. Gases have neither definite shape nor definite volume, while solids generally have both. Plasma, another state of matter, is an ionized gas rather than a liquid.