Commonly just shortened to Seeker. The Seeker is a type of person in the Sword of Truth series by Terry Goodkind. There is only one Seeker, and they carry the Sword of Truth.
Wizards long before the start of the story made the Sword of Truth. It took them quite a few tries to get it just right.
The magic of the sword is that the Seeker can't hit someone they know isn't their enemy. They can swing it at an innocent all day long, but the sword will stop short every time.
The only exception to this is if they can turn the blade white with righteous anger. Then there is no limit, but the toll this takes on their emotions is almsot unbearable.
The Sword also stores the memories of how to fight that each Seeker possesses, so that the new Seeker can draw on them. Once they do this, they're Bad to the Bone.