Birr

Birr, n. 1. A whirring sound, as of a spinning wheel.

2. A rush or impetus; force.

Birr (?), v. i. [imp. & p. p. Birred (?); p. pr. & vb. n. Birring.] [Cf. OE. bur, bir, wind, storm wind, fr. Icel. byrr wind. Perh. imitative.] To make, or move with, a whirring noise, as of wheels in motion.