/ Dictionary / Index J Jell-O: Meaning and Definition of Find definitions for: Jell-O Pronunciation: ( jel'ō), [key] — Trademark. Trademark. a brand of dessert made from a mixture of gelatin, sugar, and fruit flavoring, dissolved in hot water and chilled until firm. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: jell-o (Thesaurus) jellify jelly Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language