/ Dictionary / Index P psilocybin: Meaning and Definition of Find definitions for: psil•o•cy•bin Pronunciation: (sil"u-sī'bin, sī"lu-), [key] — n. Pharm. a hallucinogenic crystalline solid, CHNOP, obtained from the mushroom Psilocybe mexicana. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: psilocybin (Thesaurus) psilocin psilomelane Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language