n. A player positioned at or near a base: first baseman, second baseman or third baseman.
The Century Dictionary and Cyclopedia
n. Any one of the three players who in the game of base-ball are stationed at first, second, and third bases.
Word Usage
"Local fans thought the Colonel bore a resemblance to Randy Bass, a bearded power hitter and first baseman from the U.S. who played for the team at the time."