[ pī′lō-ĭ-rĕkshən ]
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Erection of hair.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.


What does piloerection mean?

Piloerection is a technical term for what happens when your hair stands up, such as when you’re cold, scared, or excited.

We popularly call this goose bumps (or goose pimples, gooseflesh, or goose skin). Other technical names for it are horripilation and cutis anserina.

Piloerection doesn’t only happen in humans. When some animals get startled or threatened, their fur raises in response. (When the fur becomes raised in this way on the neck, such as on a dog or cat, we say they’ve raised their hackles.)

The same thing happens in humans, and is usually most noticeable in places where we don’t have much hair or the hair is very fine, such as the arms and neck.

Example: A well-known example of piloerection in animals is the raising of a porcupine’s quills.

Where does piloerection come from?

The first records of the word piloerection come from the 1930s. It’s formed from pilo-, meaning “hair,” and erection, referring to the act or state of being raised. (The pil part of horripilation can be traced back to the same root as the pilo- in piloerection—the Latin pilus, meaning “hair.”)

Piloerection in response to being scared has led to the term hair-raising to describe a frightening experience. Biologically speaking, piloerection is an involuntary reaction called the pilomotor reflex. It involves the contraction of tiny muscles at the base of each hair follicle called arrector pili (a name that’s based on the same roots as piloerection). This contraction results in the hairs standing up. When there’s no hair there or the hairs are very small, this appears as bumps on the skin. These bumps are said to resemble those on the skin of a goose that has had its feathers plucked, hence the name goose bumps.

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What are some synonyms for piloerection?

What are some words that share a root or word element with piloerection

What are some words that often get used in discussing piloerection?


How is piloerection used in real life?

Piloerection is a technical term. In everyday conversation, people usually just say goose bumps or similar terms.


Try using piloerection!

Which of the following things can trigger piloerection?

A. fear
B. cold
C. excitement
D. all of the above