/ Dictionary / Index Y yellow jacket: Meaning and Definition of Find definitions for: yel'low jack"et Pronunciation: [key] any of several paper wasps of the family Vespidae, having black and bright yellow bands. a yellow capsule of phenobarbital. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. yellow jack yellow jasmine Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language