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

By the time Colorado changed its laws, Liberato had become a regular user of LSD and psilocybin, and had begun teaching others how to use them for medicinal purposes at a healing center near Colorado Springs. —Frederick Dreier, Outside, 22 Jan. 2026

Last July, officials found chocolate bars from another brand called West Coast Gold Caps contained psilocybin. —Tiney Ricciardi, Denver Post, 20 Jan. 2026

Troopers also found more than $5,000 in cash, as well as five ounces of psilocybin mushrooms, six pounds of concentrated cannabis, 18 pounds of cannabis flower and more than a dozen mature marijuana plants, officials said. —Muri Assunção, New York Daily News, 20 Jan. 2026

In New Mexico, state lawmakers took an unconventional step by legalizing psilocybin for therapeutic use and prohibiting employer discipline based solely on its legal use outside of work. —Alonzo Martinez, Forbes.com, 16 Jan. 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)