2. A game played with a bat and ball by two opposing teams of nine players, each team playing alternately in the field and at bat, the players at bat having to run a course of four bases laid out in a diamond pattern in order to score.
3. The ball that is used in this game.
4. Games A game of darts in which the players attempt to score points by throwing the darts at a target laid out in the form of a baseball diamond.
5. Often used to modify another noun:
a baseball hat; baseball gloves.