/ Dictionary / Index H hydroxyl: Meaning and Definition of Find definitions for: hy•drox•yl Pronunciation: (hī-drok'sul), [key] — adj. containing the hydroxyl group. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: hydroxyl (Thesaurus) hydroxyketone hydroxylamine Related Content Daily Word Quiz: profiterole Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language