Backdoor Slider - A pitch thrown by the defensive pitcher that appears to move away from the batter and then comes back in, usually for a strike.

Balk - A motion by the pitcher or catcher that is illegal. All base runners are allowed to advance one base. A balk can occur when: the pitcher fails to come to a complete stop before delivering the pitch; the pitcher steps towards home plate and delivers the ball to a base; or the catcher moves out of the catcher's box while the pitch is being thrown.

Ball - A pitch that is not in the strike zone of the batter and is not swung at by the batter. Also another name for baseball.

Base - One of the four locations on the baseball field that are considered safe areas for the offensive runner. A runner must successfully touch all four bases before scoring a run. The base are designated in the order that the runner advances: first base, second base, third base, and home plate. Home plate is also the location from where the batter stands to bat. All bases except for home plate consist of soft material covered with a white canvas. Home plate is constructed of a slab of white rubber trimmed in black that has five sides. Distances between bases vary according to the level of play but are always located at an equal distance from each other. In Major League Baseball, the distance between bases is 90' or about 27.4 meters.

Base Coach - An instructor of the offensive team that gives advice to the base runners and the hitters. During offensive play, there are two base coaches on the field, one next to first base and the other next to third base. When a base coach is giving advice to a hitter it is usually done with coded signals that can not be interpreted by the defensive team.

Base on Balls - The award of a free pass to first base given to a batter after a pitcher throws four pitches out of the strike zone. Usually a base on balls is the results of poor control by the pitcher but also maybe intentional. Also known as a walk.

Baseball - A game played by two teams that consists of hitting a ball, running bases, and catching the ball. The ball used in the game of baseball.

Baseball Field - The area where baseball is played consisting of an infield, outfield, fair territory, foul territory, and bases. The surface of the field usually consists of grass, astro-turf, dirt, or a combination of these three. The dimensions of the field vary depending upon the level of play and the location.

Bases Empty - A situation where there are no offensive players on base.

Bases Loaded - The situation where there is an offensive player at all bases.

Bat - A piece of equipment used by the offensive team to hit the baseball thrown by the pitcher. Usually made of wood but can be made of metal.

Batter - The offensive player when located in the batter's box next to home plate. The batter is responsible for swinging the bat in an attempt to hit the ball.

Batting Average - The average of a player that is obtained by dividing the total hits by the number of at bats. The batting average is always expressed to three decimal places and is never represented as a percentage.

Batting Glove - A piece of equipment worn by the batter on the hand(s) to increase the grip on the bat.

Bean - The act of the pitcher hitting the batter during the delivery of the pitch.

Bench - The seating next to field where team members not actively participating, coaches, and the manager are located. Also known as the dugout.

Big Leagues - Slang term for the Major Leagues of baseball.

Brush Back - The intentional act of the defensive pitcher to throw the ball in close to the batter, usually within inches of the player. The intent of this pitch is to get the batter to move away from the plate. It is usually followed by a pitch outside.

Bullpen - The location on the field reserved for the pitchers awaiting entry into the game. It is utilized by the pitcher to warm up before entering the game.

Bunt - A play by the offensive team where the batter does not swing at the ball but rather holds the bat perpendicular to home plate to make contact with the baseball. It is most often used as a strategic play to advance the runners to the next base. A ball that is bunted foul with two strikes is an out.