Ace : A team’s best starting pitcher.
Alley : The section of the outfield between the outfielders. Also called “gap.”
Around the horn : A double play going from third base to second to first.
Backdoor slider: A pitch that appears to be out of the strike zone, but then breaks back over the plate.
Bag: A base.
Baltimore chop: A ground ball that hits in front of home plate (or off of it) and takes a large hop over the infielder’s head.
Bandbox: A small ballpark that favors hitters.
Bang-bang play: A play in which the base runner hits the bag a split-second before the ball arrives or vice versa.
Basket catch: When a fielder catches a ball with his glove near belt level.
Beanball: beanball is a pitch, similar to a brushback pitch but actually intended to hit the batter as it is thrown at the head. It is rarely used as a strategic weapon, and is usually an act of anger and frustration; however, batters facing known headhunters are given a reason to fear a beanball and may alter their approach to hitting in the interests of self-protection, perhaps giving some strategic advantage to the pitcher. Some pitchers have been known to throw beanballs in response to giving up home runs. Teams with heated rivalries often find several beanballs exchanged in a season
Bronx cheer: When the crowd boos.
brushback: A pitch that nearly hits a batter.
Bush Also “bush league.”: An amateur play or behavior.
Can of Corn: An easy catch by an infielder.
Fireman: A teams closer or late-inning relieve pitcher
Nail down : As in “nail down a victory.” Refers to a relief pitcher finishing off the game.
On the screws : When a batter hits the ball hard. Also “on the button.”
Painting the black: When a pitcher throws the ball over the edge of the plate.
Pea :A ball traveling at high speed, either batted or thrown.
Pepper: Pepper is a common pre-game exercise where one player bunts brisk grounders and line drives to a group of fielders who are standing about 20 feet away.
Pick: A good defensive play by an infielder on a ground ball. Also a shortened version of “pick-off.”
Pickle: A rundown or hot box.
Punchout: A strikeout.