An embedment is a type of union between a resistant solid and another immobile solid with respect to an also immobile reference system, which completely eliminates the possibility of movement of one solid with respect to the other at the points of the embedment. Mathematically, an embedment reduces the number of degrees of freedom "Degree of freedom (engineering)") of its points. In the set of embedment points E the displacement vector satisfies the following boundary conditions:

Two rigid solids joined by an embedment mechanically form a rigid solid. In beam theory, an elastic bar that has an embedment at one end has three fewer degrees of freedom than if said embedment did not exist. In a planar rigid knot structure, each embedment eliminates 3 degrees of freedom. In a three-dimensional structure it eliminates six degrees of freedom. In a plate or sheet each embedded contour also eliminates six degrees of freedom at each point on the contour.