Third baseman

defensive position in baseball and softball, played on the far left end of the infield near third base

A third baseman is a person in baseball who covers third base.

The position of the third baseman

Somebody playing third base must have good reflexes and be able to react fast, because he is one the closest infielders to the batter. He must also have a good arm, because third basemen sometimes have to throw to second base as a part of a double play.