/ Dictionary / Index J jac: Meaning and Definition of Find definitions for: jac Pronunciation: ( jak), [key] — n. Informal. jacket. J.A.C. Pronunciation: [key] Junior Association of Commerce. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Jabrud jacal Related Content Daily Word Quiz: frugal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language