Bristle refers to a short, stiff hair or fiber, often found on animals or plants. In animals, bristles can be seen on the bodies of certain species, such as pigs or hedgehogs, providing protection and sensory functions. In plants, bristles may appear on leaves or stems, serving various purposes like deterring herbivores. In addition to its biological context, the term "bristle" can also describe the action of becoming stiff or standing upright, often in response to fear or aggression. For example, a cat may bristle its fur when feeling threatened, making it appear larger to potential predators.