balloon a slow-pitched ball that, to the batter, appears big and easy to hit.
baptism the roughing up of a smooth, new baseball with special mud, performed by the umpire prior to a game.
barrel the heavy, top, or hitting portion of a bat.
base on balls a walk. A batter's pass to first base after the pitcher pitches four balls out of the strike zone, at which the batter doesn't swing.
bases loaded runners on every base.
basket catch catching a fly ball at belt level with cupped hand and glove, a risky technique.
batfest an inning or game with an unusually high number of hits.
batter's box either one of the 6-foot by 4-foot rectangles a player must stand in while at bat.
battery collective term for the pitcher and catcher.
batting average a percentage determined by dividing the number of hits a player has by the number of times he has been up to bat. 1.000, would be perfect.
More realistically, however, .300 is excellent and .400 or above is extraordinary and rarely achieved.
bazooka a powerful throwing arm.
bean to hit a batter in the head with a pitched ball.
beanball a ball intentionally pitched at the batter's head to intimidate or to move him back away from the plate.
beanball war retaliatory pitches at a batter's head by both teams.
behind in the count referring to a batter, having more strikes than balls; referring to a pitcher, having more balls than strikes.
bellywhopper a head-first, diving slide into a base.
benchwarmer a player who rarely plays and can usually be seen sitting on the bench.
big guns artillery.
bleachers the cheap seats or benches located around the outfield.
bloop to hit a short fly ball that lands between the infielders and outfielders for a hit. Also known as a Texas Leaguer.
blooper a short fly ball that lands between the infielders and outfielders for a hit.
blow it by to pitch a ball so fast that the batter can't possibly hit it.
blow smoke to throw fastballs; also throw smoke.
bobble commonly used term for a hit ball that is mishandled or dropped.
box score in newspaper sports sections, a statistical rundown of a game.
box seats the best and most expensive seats in a ballpark, located around first base, third base, and home plate.
boys of summer originally a name for the Brooklyn Dodgers of the 1950s but now connoting all baseball players.
bread-and-butter pitch a pitcher's most effective pitch.
breaking said of a curveball as it "breaks" high, low, fast, or slow.
breaking ball any pitch that alters its trajectory by rising, dipping, or curving.
break the wrists the determining factor in whether a batter has taken a full swing at the ball, missed, and produced a strike; to swing the arms and turn the wrists far enough to be considered a strike.
break-up slide an intentional sliding collision with a defensive player to break up a double or triple play.
brushback pitch a ball pitched deliberately close to the batter's body in order to move him back away from the plate. This is a method of regaining some of the strike zone the batter had crowded out.
bug on the rug a ball bouncing elusively on artificial turf.
bullpen located beyond the outfield, one of two practice or warmup areas for relief pitchers.
bullpen ace a team's most effective relief pitcher.
bunt a lightly hit ball that rolls only a few feet from home plate, used as a sacrifice hit to advance a base runner. If executed well, it can also serve as a hit to get the batter to first.
bush slang for unprofessional or unsportsmanlike play, named after lesser minor leagues such as A or AA, otherwise known as the bush leagues.
bush league the A or AA minor leagues or lower leagues.
buzzer a ball pitched so fast that it literally "buzzes."
cannon a powerful throwing arm.
caught leaning of a base runner who has taken too much of a lead from the base, picked off for an out.
caught looking of a batter, called out on strikes.
cellar commonly used term for last place.
chalk the white powder used to mark lines and boxes in the playing field. Lime is also used.
change-up a ball thrown to resemble a fastball but that actually moves slowly, used to throw off a batter's timing. Also, any slow ball thrown after a number of successive fastballs, to damage a batter's timing.
check swing a half swing; a partial swing not counted as a strike because the wrists weren't broken.
cheese slang for a fastball. Also known as cheddar.
choke to perform badly in a critical situation. Also, to choke in the clutch.
choke up on the bat to place the hands high up on the handle of the bat to achieve greater control of the swing.