( especially BrE ) ( NAmE usually whir ) / wɜː(r); NAmE / verb , noun
■ verb
( -rr- ) [ v ] to make a continuous low sound like the parts of a machine moving :
The clock began to whirr before striking the hour.
■ noun
(also whir·ring ) [ usually sing. ] a continuous low sound, for example the sound made by the regular movement of a machine or the wings of a bird :
the whirr of a motor
There was a whirring of machinery.
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WORD ORIGIN
late Middle English (in the sense move with a whirring sound ): probably of Scandinavian origin; compare with whirl .