/ Dictionary / Index J Jr.: Meaning and Definition of Find definitions for: Jr. Pronunciation: [key] Journal. Junior. jr. Pronunciation: [key] junior. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: jr (Thesaurus) J/psi particle JRC Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language