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

And what we found in that research too was that it wasn't obviously solely the psilocybin or the psychedelic components — it was that, compounded with untreated and unchecked grief for however many years.

From Salon • Aug. 28, 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

An alternative theory is that psilocybin is a chemical defense against insects.

From Science Daily • Jan. 9, 2024