/ Dictionary / Index J jack staff: Meaning and Definition of Find definitions for: jack' staff" Pronunciation: [key] a flagstaff at the bow of a vessel, on which a jack is flown. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Jacksonville Beach jackstay 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