The Collaborative International Dictionary of English v.0.48:

Whur \Whur\, v. i. [Probably of imitative origin. Cf. Hurr,
   Hurry, Whir.]
   [1913 Webster]
   1. To make a rough, humming sound, like one who pronounces
      the letter r with too much force; to whir; to birr.
      [1913 Webster]

   2. To snarl or growl, as a dog. --Halliwell.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Whur \Whur\, n.
   A humming or whirring sound, like that of a body moving
   through the air with velocity; a whir.
   [1913 Webster]