birr /ˈbɝ, ˈbɪr/
  衝量
  Birr v. i. [imp. & p. p. Birred p. pr. & vb. n. Birring.]  To make, or move with, a whirring noise, as of wheels in motion.
  Birr, n.
  1. A whirring sound, as of a spinning wheel.
  2. A rush or impetus; force.
  ◄ ►
  birr
       n 1: the basic unit of money in Ethiopia; equal to 100 cents
       2: sound of something in rapid motion; "whir of a bird's
          wings"; "the whir of the propellers" [syn: whir, whirr,
           whirring]
       v : make a soft swishing sound; "the motor whirred"; "the car
           engine purred" [syn: whizz, whiz, whirr, whir, purr]