/ Dictionary / Index J jack bean: Meaning and Definition of Find definitions for: jack' bean" Pronunciation: [key] a bushy tropical plant, Canavalia ensiformis, of the legume family, grown esp. for forage. the white seeds of this plant. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. jackatar jack block Related Content Daily Word Quiz: penury Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language