erectile hairs along the back of a dog or other animal that rise when it is angry or alarmed.
The dog stared, ears flattening, and she saw his hackles rise along his spine.
a long, narrow feather on the neck or saddle of a domestic rooster or other bird.
Even before they hit the ground both birds fan their hackles out, resembling nothing so much as a suddenly opened umbrella.
a steel comb for separating flax fibers.