/ Dictionary / Index A arcanum: Meaning and Definition of Find definitions for: ar•ca•num Pronunciation: (är-kā'num), [key] — pl. -na Often,a secret; mystery. a supposed great secret of nature that the alchemists sought to discover. a secret and powerful remedy. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: arcanum (Thesaurus) arcanist arcanum arcanorum* Related Content Daily Word Quiz: clairvoyant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language