To make a body or part or surface fixed so that it does not move when the load is applied to that body. It remains Rigid (stiff) without any deformation. This is rigid support.
In Ansys Workbench select the part, body or any face and assign Fixed support to it so that it remains Rigid.
The constraints given to any point, edge, curve, faces etc. such that all the degree of freedoms are restricted, is said to be RIGID SUPPORT / FIXED SUPPORT.