Furring /(?)/

Fur·ring

Furring

n.
  1. The leveling of a surface, or the preparing of an air space, by means of strips of board or of larger pieces. See Fur, v. t., 3. (Carp.)
  2. Double planking of a ship's side. (Shipbuilding)
  3. A deposit from water, as on the inside of a boiler; also, the operation of cleaning away this deposit.