/ Dictionary / Index J jack mackerel: Meaning and Definition of Find definitions for: jack' mack"erel Pronunciation: [key] a mackerellike food fish, Trachurus symmetricus, of Pacific coastal waters of the U.S. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. jacklighter jack Mormon 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