WHIRR
whir, whirr, whirring, birr
(noun) sound of something in rapid motion; “whir of a bird’s wings”; “the whir of the propellers”
churr, whirr
(verb) make a vibrant sound, as of some birds
whizz, whiz, whirr, whir, birr, purr
(verb) make a soft swishing sound; “the motor whirred”; “the car engine purred”
Source: WordNet® 3.1
Etymology
Verb
whirr (third-person singular simple present whirrs, present participle whirring, simple past and past participle whirred)
To move or vibrate (something) with a buzzing sound.
(intransitive) To make a sibilant buzzing or droning sound.
(transitive) To cause (something) to make such a sound.
Synonyms
• (make a sibilant buzzing or droning sound): buzz, drone, hum, purr, whine, whistle, whizz
• (cause (something) to make such a sound)
Noun
whirr (plural whirrs)
A sibilant buzz or vibration; the sound of something in rapid motion.
A bustle of noise and excitement.
Synonyms
• (sibilant buzz or vibration): buzz, drone, hum, purr, whine, whistle, whizz
• (bustle of noise and excitement): bustle, hustle
Source: Wiktionary