/ Dictionary / Index I Isaac: Meaning and Definition of Find definitions for: I•saac Pronunciation: (ī'zuk), [key] — n. a son of Abraham and Sarah, and father of Jacob. Gen. 21:1–4. a male given name: from a Hebrew word meaning “laughter.” Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: isaac (Thesaurus) Isa. Isaacs Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language