- A measure of the energy dissipation due to a flow in a viscous system. In medicine and physiology, usually a measure of the energy dissipation in the flow of liquids, sols, or gels within cells and tissues, or of fluids ( e.g., blood, respiratory gases) in tubes. The v. is the pressure gradient from one end to the other of the flow path when unit flow occurs. The relationship between viscosity and v. is of the same nature as that between specific resistance, or resistivity, of a conductor material and the resistance of a particular conductor made from that material.
Medical dictionary. 2011.