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

Two states — Oregon and Colorado — have legalized psychedelic therapy with psilocybin. —Matthew Perrone, Los Angeles Times, 19 Apr. 2026

Beyond symptom reduction, patients receiving psilocybin were significantly more likely to achieve meaningful clinical improvement -- response rates were nearly three times higher, and remission rates were about four times higher than the control groups. —Nicholas Kerr, ABC News, 18 Apr. 2026

And administration officials vetoed a fast-track approval process for a psilocybin treatment from Compass Pathways earlier this year. —Daniel Payne, STAT, 18 Apr. 2026

Three other states, Colorado, New Mexico and Oregon, have legalized psilocybin mushrooms for therapeutic use. —Esme Murphy, CBS News, 11 Apr. 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)