What is Molar ionic conductivity?

The conductivity $\kappa$ of a solution (in $\mathrm{S}/\mathrm{m}$) measures how well it carries current through the motion of its ions. The molar ionic conductivity $\lambda_i$ of an ion is its contribution per mole per unit volume; its value at infinite dilution, $\lambda_i^\circ$, is a constant of the ion and the solvent at a given temperature.