Strictly speaking thermodynamics only describes systems at equilibrium or systems which undergo some change, at the end of which they have time to relax back to an equilibrium state. The signature of a thermodynamic system is the huge reduction of the number of degrees of freedom required to describe the state of the system.
Non equilibrium is a weak characterization and actually one can distinguish different levels of departure from thermodynamic equilibrium.
For example, hydrodynamics corresponds to a case where, due to a macroscopic movement of the fluid, if the flow is not too complex, a three dimensional velocity vector field is required, in addition to a couple of thermodynamic scalar fields which describe the local thermodynamic equilibrium.
The special case of thermodynamic systems brought slightly out of equilibrium is also interesting. In that case it is possible to study the fluxes which try to restore equilibrium and to get information about transport coefficients.
However, one has to take into account that major departures from equilibrium are possible, basically requiring to go to detailed descriptions using a huge number of degrees of freedom.