  A new formulation of the plasma resistivity that arises from the collisional
momentum-transfer rate between electrons and ions is presented. The resistivity
computed herein is shown to depend not only on the temperature and density but
also on all other polynomial velocity-space moments of the distribution
function, such as the pressure tensor and heat flux vector. The exact
expression for the collisional momentum-transfer rate is determined, and is
used to formulate the nonlinear anisotropic resistivity. The new formalism
recovers the Spitzer resistivity, as well as the concept of thermal force if
the heat flux is assumed to be proportional to a temperature gradient.
Furthermore, if the pressure tensor is related to viscous stress, the latter
enters the expression for the resistivity. The relative importance of the
nonlinear term(s) with respect to the well-established electron inertia and
Hall terms is also examined. The subtle implications of the nonlinear
resistivity, and its dependence on the fluid variables, are discussed in the
context of magnetized plasma environments and phenomena such as magnetic
reconnection.
