/ Dictionary / Index B butyl: Meaning and Definition of Find definitions for: bu•tyl Pronunciation: (by'til, byt'l), [key] — adj. Chem. containing a butyl group. Bu•tyl Pronunciation: (by'til, byt'l), [key] — Trademark. Trademark. a brand of synthetic rubber prepared by polymerization of butylene containing little butadiene, particularly useful for inner tubes of automobile tires because of its leakproof qualities. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: butyl (Thesaurus) butut butyl acetate Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language