"Corporeal" and "discorporate" refer to the bodily states of certain Fellowship Sorcerers. Discorporate Sorcerers have no physical body, and can travel almost instantaneously across Paravia. They can choose to have some sort of ghostly manifestation which shows them as they were when they had a body, but generally only do this when they are speaking to someone.
There are three Sorcerers in the story who are initially classified as discorporate:
Discorporate Sorcerers lack a physical body that can be used to anchor them to the physical world. Some Fellowship wards can only be repaired by a pair of Sorcerers, one corporeal and one discorporate, to work on both sides of the veil. Discorporate Sorcerers are also wary around the boundaries of a grimward, whose protections can obliterate them.
|Spoiler warning: Contains plot elements from Peril's Gate.
Being discorporate is a permanent state. However, it is revealed that Davien overcame these limitations through years of restless creativity. With the ability to become truly physical at will, Davien is able to avoid a Koriani trap created under the assumption that he lacked a physical presence.