/ Dictionary / Index B base runner: Meaning and Definition of Find definitions for: base' run"ner Pronunciation: [key] — Baseball. Baseball. a player of the team at bat who is on base or is trying to run from one base to another. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. base rate bases 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