Specific resistance or resistivity of a material is the resistance of a wire of that material of unit length and unit area of cross section.
i.e. Resistivity $\mathit{\rho }=\frac{\mathrm{R}\mathit{a}}{\mathit{l}}$
The S.I. unit of specific resistance is ohm $\times$ meter (or $\mathit{\Omega }\mathit{m}$ ).