Source : Webster's Revised Unabridged Dictionary (1913)

Wraith \Wraith\, n. [Scot. wraith, warth; probably originally, a
   guardian angel, from Icel. v["o]r[eth]r a warden, guardian,
   akin to E. ward. See {Ward} a guard.]
   1. An apparition of a person in his exact likeness, seen
      before death, or a little after; hence, an apparition; a
      specter; a vision; an unreal image. [Scot.]

            She was uncertain if it were the gypsy or her
            wraith.                               --Sir W.
                                                  Scott.

            O, hollow wraith of dying fame.       --Tennyson.

   2. Sometimes, improperly, a spirit thought to preside over
      the waters; -- called also {water wraith}. --M. G. Lewis.

Source : WordNet®

wraith
     n : a mental representation of some haunting experience; "he
         looked like he had seen a ghost"; "it aroused specters
         from his past" [syn: {ghost}, {shade}, {spook}, {specter},
          {spectre}]