psi·​lo·​cy·​bin | \ ˌsī-lə-ˈsī-bən How to pronounce psilocybin (audio) \

Definition of psilocybin

: 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

Rocky Mountain Poison & Drug Safety’s hotline reports only two psilocybin cases since May, the same rate as before. Andrew Kenney, The Denver Post, "In Denver, the spores of a psychedelic mushroom boom have landed," 23 Aug. 2019 Somebody must have slipped some psilocybin into the Democrats’ potato salad at this year’s May Day picnic. Kevin D. Williamson, National Review, "The Democrats Break Left," 4 Aug. 2019 Sanjay Singhal, the founder of, is funding research into psilocybin and other psychedelics, including a planned study into micro-dosing at the University of Toronto’s Center for Psychedelic Studies. Bloomberg, The Mercury News, "First pot, then magic mushrooms? Decriminalization is spreading," 18 June 2019 But there are worries, even among some of psilocybin’s proponents, about decriminalisation. The Economist, "Magic mushrooms should be decriminalised," 7 June 2019 The altercation outside the McDonald’s stemmed from police conducting an undercover operation into alleged sales of psilocybin mushrooms in the Aspen Hill area. Dan Morse, Washington Post, "Police officer charged with assault after allegedly using leg to slam suspect’s head into sidewalk," 9 July 2019 What’s more, the team’s analysis of cicadas infected with Massospora platypediae and Massospora levispora revealed that the fungi were producing psilocybin, the hallucinogenic chemical found in certain types of mushrooms. Brigit Katz, Smithsonian, "A Fungus Causes Cicadas to Mate Like Crazy, Even After Their Butts Fall Off," 29 June 2019 Magic mushrooms, whose active ingredient is psilocybin, are in the vanguard. The Economist, "Magic mushrooms, illegal in most places, may have therapeutic uses," 7 June 2019 Matthews and Fluck very much respect the power of psilocybin. Matt Simon, WIRED, "The Heady, Thorny Journey to Decriminalize Magic Mushrooms," 10 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'psilocybin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of psilocybin

1958, in the meaning defined above

History and Etymology for psilocybin

New Latin Psilocybe, fungus genus + -in entry 1

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Last Updated

27 Aug 2019

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The first known use of psilocybin was in 1958

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psi·​lo·​cy·​bin | \ ˌsī-lə-ˈsī-bən How to pronounce psilocybin (audio) \

Medical Definition of psilocybin

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

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