psilocybin UK /ˌsʌɪ.lə(ʊ)ˈsʌɪ.bɪn/US /ˌsɪ.ləˈsaɪ.bɪn/ noun1 •A hallucinogenic alkaloid, C₁₂H₁₅N₂O·H₂PO₃, present in several species of Central American mushroom and producing effects similar to LSD. The prodrug of psilocin. formspsilocybins
