Mawson, C.O.S., ed. (1870–1938). Roget’s International Thesaurus. 1922.

Class VI. Words Relating to the Sentient and Moral Powers
Section V. Religious Affections
1. Superhuman Beings and Regions

980a. Specter.

   NOUN:SPECTER or spectre, ghost, revenant, apparition, spirit, sprite, shade, shadow, wraith, spook [now humorous], phantom, phantasm, fantasm [rare], idolum; materialization [Spiritualism], ectoplasmic manifestation; double, etheric body, etheric self, aura, auric egg, astral body, mayavi rupa, ego [all Theos. and Occultism]; vision, theophany.
  banshee, White Lady, the White Ladies of Normandy, the White Lady of Avenel [Scott]; lemures, larva or larve [Roman relig.].
  WILL-O’-THE-WISP, Friar’s lantern [See Luminary].
   ADJECTIVE:SPECTRAL, ghostly, ghostlike, spiritual, wraithlike, weird, uncanny, eerie or eery, spooky or spookish [colloq.], haunted; unearthly, supernatural.
  1. Is not this something more than fantasy!—Hamlet
  2. But soft! behold! lo! where it comes again.—Paradise Lost
  3. Of calling shapes, and beck’ning shadows dire.—Milton