/ Dictionary / Index F ferrous oxide: Meaning and Definition of Find definitions for: fer'rous ox'ide Pronunciation: [key] — Chem. Chem. a black powder, FeO, insoluble in water, soluble in acid. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. ferrous ferrous sulfate Related Content Daily Word Quiz: belligerent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language