/ Dictionary / Index M methyl: Meaning and Definition of Find definitions for: meth•yl Pronunciation: (meth'ul), [key] — adj. Chem. containing the methyl group. methyl- Pronunciation: [key] a combining form occurring in the names of chemical compounds in which the methyl group is present: methylamine. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: methyl (Thesaurus) Methuselah methyl acetate Related Content Daily Word Quiz: quandary Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language