/ Dictionary / Index A arsenous: Meaning and Definition of Find definitions for: ar•se•nous Pronunciation: (är'su-nus), [key] — adj. Chem. containing arsenic in the trivalent state, as arsenous chloride, AsCl. of or derived from arsenous acid. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. arsenopyrite arsenous acid Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language