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

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

Dr. Ramaekers adds, "Taken together, averaged and dynamic connectivity analyses suggest that psilocybin alters brain function such that the overall neurobiological pattern becomes functionally more connected, more fluid, and less modular."

From Science Daily • May 23, 2024

The two gene patterns correspond to an ancient split in the genus, suggesting two independent acquisitions of psilocybin in itsevolutionary history.

From Science Daily • Jan. 9, 2024

The Oregon Health Authority, which runs the psilocybin program, does not currently collect data from people participating in the program.

From Seattle Times • Dec. 23, 2023