liquid

State of matter between a solid and a gas. A liquid forms a level surface and assumes the shape of its container. The way that liquids behave can be explained by the kinetic theory of matter. Its atoms do not occupy fixed positions as in a crystalline solid, nor do they have total freedom of movement as in a gas. Unlike a gas, a liquid is difficult to compress, and pressure applied at one point is equally transmitted throughout (Pascal's principle). Hydraulics makes use of this property.