If you have a vision of your grandfather just before he passes away, you have seen a wraith or a ghostly image. Wraith can also mean something thin, wispy, or ghost-like.
You could call a wisp of smoke rising from a chimney a wraith or you could say that a sick aunt had been reduced to a wraith — a thin, ghostly, figure. Sometimes it's even a compliment, which shows how we idealize wraith-like fashion models. Wraith is of unknown origins, and there aren't any other words related to it.