Source : Webster's Revised Unabridged Dictionary (1913)

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

   2. To snarl or growl, as a dog. --Halliwell.

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