hackle [LME] Hackles are the long feathers on the neck of a fighting cock or the hairs on the top of a dog’s neck, which stand up when the animal is aggressive or excited. So if you make someone’s hackles rise [M19th] you make them angry or indignant. In the Middle Ages a hackle or heckle was also an instrument with parallel steel pins used to prepare flax for spinning by splitting the fibres and pulling them straight. This vigorous action was transferred to giving speakers an equally hard time or heckling them in the early 19th century. The word goes back to an ancient root related to *hook. See also tease.