The Collaborative International Dictionary of English v.0.48:

Avaunt \A*vaunt"\ ([.a]*v[add]nt" or [.a]*v[aum]nt"), interj.
   [F. avant forward, fr. L. ab + ante before. Cf. Avant,
   Advance.]
   Begone; depart; -- a word of contempt or abhorrence,
   equivalent to the phrase "Get thee gone."
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Avaunt \A*vaunt"\, v. t. & i.
   1. To advance; to move forward; to elevate. [Obs.] --Spenser.
      [1913 Webster]

   2. To depart; to move away. [Obs.] --Coverdale.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Avaunt \A*vaunt"\, v. t. & i. [OF. avanter; [`a] (L. ad) +
   vanter. See Vaunt.]
   To vaunt; to boast. [Obs.] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Avaunt \A*vaunt"\, n.
   A vaunt; to boast. [Obs.] --Chaucer.
   [1913 Webster]