/ Dictionary / Index B blue jack: Meaning and Definition of Find definitions for: blue' jack'. Pronunciation: [key] See blue•jack Pronunciation: (bl'jak"), [key] — n. a small oak, Quercus incana, of the southern U.S., having crooked branches and blue-green leaves. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Blue Island bluejacket 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