The Collaborative International Dictionary of English v.0.48:

Aroint \A*roint"\ ([.a]*roint"), interj. [Cf. Prov. E. rynt,
   rynt thee, roynt, or runt, terms used by milkmaids to a cow
   that has been milked, in order to drive her away, to make
   room for others; AS. r[=y]man to make room or way, fr. r[=u]m
   room. The final t is perh. for ta, for thou. Cf. Room
   space.]
   Stand off, or begone. [Obs.]
   [1913 Webster]

         Aroint thee, witch, the rump-fed ronyon cries. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Aroint \A*roint"\, v. t.
   To drive or scare off by some exclamation. [R.] "Whiskered
   cats arointed flee." --Mrs. Browning.
   [1913 Webster]