Generally understood ferroic media have been investigated by many authors. The majority of them have dealt with the electromagnetic nature of the domain structure of crystalline or amorphous solids. However, there exist also materials that have an internal ordered structure from the mechanical (elastic) point of view. They are called ferroelastics. The presentation proposes a thermomechanical model of irreversible and nonequilibrium processes that can run in continuous multiferroic media in which simultaneous interactions of various physical fields occur both in low and room temperatures. Attempts concerning a proposition of the constitutive theory resulting from linear and nonlinear forms of the free energy density are also presented.