A compressed fluid (also called a compressed or unsaturated liquid, subcooled fluid or liquid) is a fluid under mechanical or thermodynamic conditions that force it to be a liquid.
At a given pressure, a fluid is a compressed fluid if it is at a temperature lower than the saturation temperature. This is the case, for example, for liquid water at atmospheric pressure and room temperature. In a plot that compares pressure and specific volume (commonly called a p-v diagram), compressed fluid is the state to the left of the saturation curve.
Conditions that cause a fluid to be compressed include:
The term compressed liquid emphasizes that the pressure is greater than the saturation pressure for the given temperature. Compressed liquid properties are relatively independent of pressure.