/ Dictionary / Index B butyl group: Meaning and Definition of Find definitions for: bu'tyl group" Pronunciation: [key] — Chem. Chem. any of four univalent isomeric groups having the formula CH–. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. butylene group butyl nitrite 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