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]