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]

The Collaborative International Dictionary of English v.0.48:

Vanish \Van"ish\ (v[a^]n"[i^]sh), n. (Phon.)
   The brief terminal part of a vowel or vocal element,
   differing more or less in quality from the main part; as, a
   as in ale ordinarily ends with a vanish of i as in ill, o as
   in old with a vanish of oo as in foot. --Rush.
   [1913 Webster]

   Note: The vanish is included by Mr. Bell under the general
         term glide.
         [1913 Webster]

WordNet (r) 3.0 (2006):

vanish
    v 1: get lost, as without warning or explanation; "He
         disappeared without a trace" [syn: disappear, vanish,
         go away] [ant: appear]
    2: become invisible or unnoticeable; "The effect vanished when
       day broke" [syn: vanish, disappear, go away]
    3: pass away rapidly; "Time flies like an arrow"; "Time fleeing
       beneath him" [syn: fly, fell, vanish]
    4: cease to exist; "An entire civilization vanished" [syn:
       vanish, disappear] [ant: appear, come along]
    5: decrease rapidly and disappear; "the money vanished in las
       Vegas"; "all my stock assets have vaporized" [syn: vanish,
       fly, vaporize]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "vanish":
   abandon, abscond, be annihilated, be consumed, be destroyed,
   be done for, be gone, be no more, be wiped out, beat a retreat,
   bow out, cease, cease to be, cease to exist, clear, come to naught,
   come to nothing, conk out, dematerialize, depart, die, die away,
   die out, disappear, dispel, disperse, dissipate, dissolve,
   do a fade-out, dwindle, end, erode, evacuate, evanesce, evaporate,
   exit, expire, fade, fade away, fade out, flee, fleet, flit, fly,
   go, go away, hide, leave no trace, leave the scene, melt,
   melt away, melt like snow, pass, pass away, pass out, peg out,
   perish, peter out, quit, remove, retire, retire from sight,
   retreat, run out, sink, sink away, succumb, suffer an eclipse,
   vacate, vanish from sight, waste, waste away, wear away,
   withdraw