The Collaborative International Dictionary of English v.0.48:

Vanish \Van"ish\ (v[a^]n"[i^]sh), v. i. [imp. & p. p. Vanished
   (v[a^]n"[i^]sht); p. pr. & vb. n. Vanishing.] [OE.
   vanissen, OF. vanir (in comp.): cf. OF. envanir, esvanir,
   esvanu["i]r, F. s'['e]vanouir; fr. L. vanus empty, vain; cf.
   L. vanescere, evanescere, to vanish. See Vain, and cf.
   Evanescent,-ish.]
   [1913 Webster]
   1. To pass from a visible to an invisible state; to go out of
      sight; to disappear; to fade; as, vapor vanishes from the
      sight by being dissipated; a ship vanishes from the sight
      of spectators on land.
      [1913 Webster]

            The horse vanished . . . out of sight. --Chaucer.
      [1913 Webster]

            Go; vanish into air; away!            --Shak.
      [1913 Webster]

            The champions vanished from their posts with the
            speed of lightning.                   --Sir W.
                                                  Scott.
      [1913 Webster]

            Gliding from the twilight past to vanish among
            realities.                            --Hawthorne.
      [1913 Webster]

   2. To be annihilated or lost; to pass away. "All these
      delights will vanish." --Milton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vanished
    adj 1: having passed out of existence; "vanished civilizations"

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "vanished":
   absconded, absent, ago, all gone, annihilated, antiquated, antique,
   away, blown over, by, bygone, bypast, dated, dead, dead and buried,
   deceased, defunct, deleted, departed, disappeared, done for,
   down the drain, elapsed, expired, extinct, finished, forgotten,
   gone, gone glimmering, gone-by, had it, has-been, irrecoverable,
   kaput, kaputt, lacking, lapsed, lost, missing, no longer present,
   no more, nonattendant, nonexistent, not found, not present,
   obsolete, omitted, out of sight, over, passe, passed, passed away,
   past, perished, run out, subtracted, taken away, wanting,
   wound up