/ Dictionary / Index B Buna: Meaning and Definition of Find definitions for: Bu•na Pronunciation: (b'nu, by'-), [key] — Trademark. Trademark. a brand of synthetic rubber made by polymerizing or copolymerizing butadiene with another material, as acrylonitrile, styrene, or sodium. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: buna (Thesaurus) bun bunch Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language