psilocybin

American  

[sil-uh-sahy-bin, sahy-luh-] / ˌsɪl əˈsaɪ bɪn, ˌsaɪ lə- /

noun

Pharmacology.

1. a hallucinogenic crystalline solid, C 1 2 H 1 7 N 2 O 4 P, obtained from the mushroom Psilocybe mexicana.

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psilocybin British  

/ ˌsaɪlə-, ˌsɪləˈsaɪbɪn /

noun

1. a crystalline phosphate ester that is the active principle of the hallucinogenic fungus Psilocybe mexicana. Formula: C 12 H 17 N 2 O 4 P

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psilocybin Scientific  

/ sĭl′ə-sī′bĭn,sī′lə- /

1. A hallucinogenic compound obtained from certain mushrooms, especially of the genus Psilocybe. Chemical formula: C ₁₂ H ₁₇ N ₂ O ₄ P.

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Etymology

Origin of psilocybin

1955–60; < New Latin Psilocyb ( e ) genus of mushrooms (< Greek psīló ( s ) bare + kýbē head) + -in ²

Example Sentences

Compass Pathways confirmed an FDA priority voucher for its psilocybin candidate.

From Barron's • Apr. 24, 2026

Dr. Steven Locke, a former Harvard Medical School psychiatry professor, wrote in an email that the question of whether psilocybin has any medical applications “remains controversial.”

From Los Angeles Times • Aug. 21, 2025

There are few published clinical trials of psilocybin therapy for chronic pain, although many are ongoing, including a pilot study for fibromyalgia conducted by our team at the University of Michigan.

From Salon • May 13, 2024

Another patent lays claim to a specific, microscopic structure found in Compass’ synthetic psilocybin, which the company claims is uniquely suited for mass production.

From Seattle Times • Feb. 3, 2024

Rapid-acting antidepressants, including ketamine, scopolamine and psilocybin, have been found to have immediate and lasting positive effects on mood in patients with major depressive disorder but how these effects arise is unknown.

From Science Daily • Jan. 10, 2024