Real Dictionary

bristle
Bristles are the short hairs that grow on someone's body, especially after they have shaved. The hairs on the top of the head can also be called bristles when they are cut very short.
countable noun: Bristles are thick, strong animal hairs that feel hard and rough.
countable noun: The bristles of a brush are the thick hairs or hair-like pieces of plastic which are attached to it.
verb: If the hair on a person's or animal's body bristles, it rises away from their skin because they are cold, frightened, or angry.
verb: If you bristle at something, you react to it angrily, and show this in your expression or the way you move.
verb: If you say that a place or thing bristles with people or with other things, you are emphasizing that it contains a great number of them.

bristle in American English
any short, stiff, prickly hair of an animal or plant
to become stiff and erect, like bristles
intransitive verb: to stand or rise stiffly, like bristles
noun: one of the short, stiff, coarse hairs of certain animals, esp. hogs, used extensively in making brushes
transitive verb: to erect like bristles

bristle in British English
noun: any short stiff hair of an animal or plant
verb: to stand up or cause to stand up like bristles