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

Five hours later, when the psilocybin began to wear off, the vets removed their eye masks and found the heat of the afternoon sun. — Anderson Cooper, CBS News, 16 Aug. 2026

Studies have shown that hallucinogens such as psilocybin can trigger manic episodes and bipolar disorder even in people without a history of such concerns. — Dawn Fallik, Scientific American, 11 Aug. 2026

The order’s singling out of ibogaine, the only psychedelic mentioned by name, surprised analysts, given how much less research exists on it than on psilocybin or MDMA. — Michelle Lhooq, New Yorker, 7 Aug. 2026

Troopers also allegedly found several bags of psilocybin mushrooms, according to state police. — Justin Muszynski, Hartford Courant, 7 Aug. 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)