/ Dictionary / Index A arsenic trisulfide: Meaning and Definition of Find definitions for: ar'senic trisul'fide Pronunciation: [key] — Chem. Chem. a yellow or red crystalline substance, AsS, occurring in nature as the mineral orpiment, and used as a pigmentand in pyrotechnics. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. arsenic trioxide arsenide 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