Rigid Body Theory (RBT) constitutes an important part of the physics and science history, and an investigation field/branch with significant links/milestones extended to other parts of the physics, engineering, aerospace-aeronautics science, biology and medicine. The applications of RBT are so extent in the areas of engineering and technology, that even today there are not fixed boundaries for new advances and refinements/precision-improvements, related to those achievements already got. Classically, RBT has been developed by eminent physicists and mathematicians such as Lomonsov, Landau, Newton, Euler, Lagrange, Hamilton, D'Alembert and several others, subject to the principle of non-deformable state for the analyzed solid in arbitrary-movement/dynamics/kinematics. However, that supposed inalterable group of principles, whose assertion, among many, is that many solids do not experiment deformations during any arbitrary movement, is being under critical review at present.