/ Dictionary / Index A aldehyde: Meaning and Definition of Find definitions for: al•de•hyde Pronunciation: (al'du-hīd"), [key] — n. Chem. any of a class of organic compounds containing the group −CHO, which yields acids when oxidized and alcohols when reduced. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: aldehyde (Thesaurus) Aldebaran Alden Related Content Daily Word Quiz: resilient Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language