/ Dictionary / Index J jacobsite: Meaning and Definition of Find definitions for: ja•cobs•ite Pronunciation: ( jā'kub-zīt"), [key] — n. a rare magnetic mineral, manganese iron oxide, MnFeO, similar to magnetite. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Jacobsen Jacob's ladder Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language