whir
or whirr
(wɜː) 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]