whirr vs whir

whirr and whir both are nouns.

Word	Noun	Adjective	Verb	Adverb
whirr	Yes	No	Yes	No
whir	Yes	No	Yes	No

As nouns, whirr and whir are synonyms defined as:

Other synonyms of whirr include birr, whirring.

As verbs, whirr and whir are synonyms defined as:

Other synonyms of whirr include birr, purr, whiz, whizz.

whirr (noun)	whir (noun)
sound of something in rapid motion	sound of something in rapid motion

whirr (verb)	whir (verb)
make a vibrant sound, as of some birds	make a soft swishing sound
make a soft swishing sound