piloerection
noun
pi·lo·erec·tion
ˌpī-lō-i-ˈrek-shən 
: erection or bristling of hairs due to the involuntary contraction of small muscles at the base of hair follicles that occurs as a reflexive response of the sympathetic nervous system especially to cold, shock, or fright
Note: Piloerection may also occur as a side effect from the use of a sympathomimetic drug (such as phenylephrine) or as a symptom of opioid withdrawal.
Cite this Entry
“Piloerection.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/piloerection. Accessed 5 Jul. 2026.
Copy CitationMedical Definition
piloerection
noun
pi·lo·erec·tion
ˌpī-lō-i-ˈrek-shən
: erection or bristling of hairs due to the involuntary contraction of small muscles at the base of hair follicles that occurs as a reflexive response of the sympathetic nervous system especially to cold, shock, or fright
Note: Piloerection may also occur as a side effect from the use of a sympathomimetic drug (as phenylephrine) or as a symptom of opioid withdrawal.
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