/ Dictionary / Index T tonka bean: Meaning and Definition of Find definitions for: ton'ka bean" Pronunciation: (tong'ku), [key] the fragrant, black almond-shaped seed of a tall tree belonging to the genus Dipteryx (or Coumarouna), of the legume family, esp. D. odorata, of tropical South America, used in perfumes, as a source of coumarin, and as a substitute for vanilla. the tree itself. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. tonk Tonkin Related Content Daily Word Quiz: morose Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language