psilocybin

noun

psi·​lo·​cy·​bin ˌsī-lə-ˈsī-bən 

: a hallucinogenic indole C₁₂H₁₇N₂O₄P obtained from a fungus (such as Psilocybe mexicana or P. cubensis synonym Stropharia cubensis)

Examples of psilocybin in a Sentence

Recent Examples on the Web

Now, several biotechs have advanced into late-stage trials, and the FDA could soon approve the first psilocybin treatment. —Theresa Gaffney, STAT, 31 Mar. 2026

Stephen Johnson Neuropsych Microdosing psilocybin for anxiety and depression? —Big Think, 31 Mar. 2026

Dozens of people who have participated in retreats in the US and abroad responded to a CNN callout about psilocybin retreats. —Natalia V. Osipova, CNN Money, 28 Mar. 2026

Users say taking small doses of psilocybin or LSD does everything from bolster productivity and creativity to ease symptoms of anxiety and insomnia — all without the hallucinogenic effects characteristic of a full-blown trip. —Tiney Ricciardi, Denver Post, 18 Mar. 2026

Word History

Etymology

New Latin Psilocybe, fungus genus + -in entry 1

First Known Use

1958, in the meaning defined above

Kids Definition

psilocybin

noun

psi·​lo·​cy·​bin ˌsī-lə-ˈsī-bən 

: a chemical that is obtained from a fungus and causes hallucinations

Medical Definition

psilocybin

noun

psi·​lo·​cy·​bin ˌsī-lə-ˈsī-bən 

: a hallucinogenic indole C₁₂H₁₇N₂O₄P obtained from a basidiomycetous fungus (as Psilocybe mexicana or P. cubensis synonym Stropharia cubensis)