Definition of psilocybin in US English:



  • A hallucinogenic alkaloid, found in some toadstools.

    • ‘His chapter on psychedelics begins with the modern history of such drugs, with sections then devoted to brief discussions of the subjective effects of LSD, psilocybin, mescaline, DMT, ayahuasca, MDMA, and marijuana.’
    • ‘Some hallucinogens, such as PCP and MDMA are addictive, while others, such as LSD, psilocybin, and mescaline are not.’
    • ‘While regular hallucinogens like psilocybin stimulate new neurological connections, the Amanita muscaria does something extra.’
    • ‘LSD use also produces tolerance for other hallucinogenic drugs such as psilocybin and mescaline, but not to drugs such as marijuana, amphetamines, and PCP, which do not act directly on the serotonin receptors affected by LSD.’
    • ‘The mechanisms of action of the hallucinogens lysergic acid and psilocybin (magic mushrooms) are complex, with various effects on serotonergic, dopaminergic, and adrenergic receptors.’


1950s: from modern Latin Psilocybe (genus name), from Greek psilos ‘bald’ + kubē ‘head’.