Merriam-Webster Collegiate Dictionary - whir

 I. verb  also ~r  (~red; ~ring)  Etymology: Middle English (Scots) quirren, probably of Scandinavian origin; akin to Danish hvirre to ~l, ~  Date: 15th century  intransitive verb to fly, revolve, or move rapidly with a ~ hummingbirds ~ring past  transitive verb to move or carry rapidly with a ~  II. noun  also ~r  Date: 1677 a continuous fluttering or vibratory sound made by something in rapid motion the ~ of machinery