The term Ghost, began circulating sometime after World War III but the origin dates back to early decades of the last century. It refers to an individual's mind or essence of being, their soul perhaps — although that term is somewhat of an antique in this day since the soul denotes spirituality while the ghost is a subject of science. Its what differentiates a human being from a robot. Regardless of how much the biological is replaced with cybernetic, a ghost retains its humanity and individuality. Usually, such a term, separating it from the Shell, was meaningless. One was their Ghost in their Shell. Separation could not exist. That is no longer the case. One now can exist without a shell. And Shells can exist without Ghosts. The Shell refers to the body, organic or unorganic.
One can even transfer a ghost from one Shell to another. Existing without a proper Shell (even the basic rudimentary forms like brainboxes) usually results in degredation. A consequence of Ghost and Shell separation arose in criminology. When a criminal is convicted of a crime, a technical analysis is done either determining if the crime was committed due to material defects in the biological or the cybernetic systems in the criminal brain. If a mechanical defect arises, said defect is repaired and the convict is released. If the crime results from the individual's ghost, the process becomes more invasive. Anything from personality reprogramming to full ghost erasure can occur. If the Ghost contained itself in a prosthetic body, the body would usually be sold off for parts.