Diluent

Diluent is a term describing a diluting agent. Certain fluids are too viscous to be pumped easily or too dense to flow from one particular point to the other. This can be a problem because it might not be economically feasible to transport such 'heavy' fluids.

To ease the restricted movement of such fluids, diluents (or thinners or dilutants) are used – which act to decrease the viscosity of these fluids, thereby also decreasing the pumping/transportation costs. For example, nail polish thinner is used to improve the consistency of nail polish making it more applicable.