Major League - An organization of professional baseball players in the United States.

Manager - The person on the field that is responsible for the team's actions, communicates with the umpire and opposing manager, and advises strategies for the play of the game.

Minor League - An organization of 19 professional leagues in the United States.

Mound - An area that is higher in elevation than the surrounding ground that is used by the pitcher for leverage in delivering the ball to the catcher. Also known as the pitching mound.

No Hitter - The rare event where the pitcher(s) does not allow a hit to the batter during the course of an entire game. If the pitcher(s) did not allow a base runner then the game is recorded as a perfect game.

Offense - The team or player batting the ball or running the bases.

On Base Percentage - The statistical information on an offensive batter that reflects the number of times a batter gets on base in comparison to the number of official at bats of the player. Also known as on base average.

On Deck - The player that is schedule to bat next after the current batter. This player is required to stand in the on deck circle that is reserved to practice swings.

Out - The retirement of one of the offensive players. There are 3 outs per offensive period, 6 outs per inning, and 54 outs per nine inning game. The defensive team can get an offensive player out by tagging the offensive player with the ball, touching the base while holding the ball before the offensive player reaches it, striking the batter out, or catching the offensive player's batted ball in the air before the ball touches the ground. The umpire may call the offensive player out for violation of one of the rules of baseball.

Outfield - The area of the field that is most distant from home plate. There are three positional players in the outfield: left fielder, center fielder, and right fielder.

Outfield Wall - A wall located in the outfield that determines the limits of the playing field. Any ball hit over the wall in fair territory is a home run.

Outfielder - A defensive player that is positioned in the outfield. There are three positional players in the outfield consisting of the left fielder, center fielder, and right fielder.

Outside Pitch - A pitch that is thrown out of the strike zone away from the batter.

Overslide - The act of an offensive runner sliding past the base. Usually due to the runner commencing the beginning of the slide to late.