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

Psychedelics such as ibogaine, ayahuasca, psilocybin, LSD and MDMA have all shown promising results in treating mental health conditions including PTSD, traumatic brain injury and treatment-resistant depression. —Clara Harter, Los Angeles Times, 26 June 2025

The governor’s pardon, via an executive order, applies to anyone convicted of possession of psilocybin or psilocin at the state level. —Tiney Ricciardi, Denver Post, 18 June 2025

Under the original bill, psilocybin could have been used to treat PTSD, but an amendment approved by the lower chamber of the state legislature expanded the ability of the board to approve other illnesses that could be treated with psilocybin, including depression. —Annabella Rosciglione, The Washington Examiner, 22 Apr. 2025

Oregon became the first state to legalize psilocybin’s therapeutic use in 2020, though some cities have banned the drug. —Chad De Guzman, Time, 18 June 2025

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)