Scientific basis for describing a deformable solid as a nonlinear hierarchically organized system has been developed. It has been predicted theoretically and verified experimentally that primary plastic shear strains in a loaded solid are nonlinear waves of local structural transformations in 2D surface layers and internal interfaces with no long-range order. The development of these nonlinear waves owes to multiscale self-consistency of plastic flow at different structural-scale levels. Strain-induced defects of any type nucleate in highly excited hydrostatic tension zones that arise as nonlinear waves of channeled plastic flow propagate in the 2D systems. A regular occurrence of the zones defines the nature of plastic strain localization. It is suggested that a local curvature of vortex plastic flows be considered as a generalized structural parameter to provide multiscale plastic flow consistency in a material in the entire hierarchy of structural scales, including its electronic subsystem. The generalized structural parameter allows an adequate description of a deformable solid in different thermodynamic states, including highly nonequilibrium nanostructured materials