Words

whirr

whir

or

whirr

(wɜːPronunciation for whirr)
  noun
    1 a prolonged soft swish or buzz, as of a motor working or wings flapping
    2 a bustle or rush

▷ 
verb whirs, whirrs, whirring or whirred
    3 to make or cause to make a whir
  [C14: probably from Scandinavian; compare Norwegian kvirra, Danish hvirre; see whirl]