/ Dictionary / Index T third baseman: Meaning and Definition of Find definitions for: third' base'man Pronunciation: [key] — Baseball. Baseball. the player whose position is third base. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. third base third class Related Content Daily Word Quiz: winsome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language