/ Dictionary / Index G great-granduncle: Meaning and Definition of Find definitions for: great-grand•un•cle Pronunciation: (grāt"grand'ung"kul), [key] — n. an uncle of one's grandfather or grandmother. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. great-grandson great gray owl Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language