Symbol ρ. A measure of a material's ability to oppose the flow of an electric current. The resistivity of a material is given by RA/l, where R is the resistance of a uniform specimen of the material, having a length l and a cross-sectional area A. It is usually given at 0°C or 20°C and is measured in ohm metres. It was formerly known as specific resistance.
http://www.kayelaby.npl.co.uk/general_physics/2_6/2_6_1.html Values of resistivity for a range of materials at the NPL website