A diluent (also referred to as a filler, dilutant or thinner)'s 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 problematic, because it mightn't be economically feasible to transport such fluids in this state. To ease this restricted movement, diluents are added. This decreases the viscosity of the fluids, thereby also decreasing the pumping/transportation costs. One industrial application's the transpo… (More on Diluent)