An instrument or tool used in hackling or straightening the fibres of flax. It consists of several rows of long sharp iron teeth, fixed in a piece of wood, and placed with their points upwards before the workman, who strikes the flax, which he holds in his hand, upon the teeth of the hackle, drawing it quickly through them. According to the quality of the flax, or the purpose for which it is designed, the workmen use a hackle with finer, coarser, or wider teeth; but generally using a coarse one first and a finer afterwards. See Flax.