Glossary of baseball terms

The following is an alphabetical list of selected unofficial and specialized terms, phrases, and other jargon used in baseball, and explanations of their meanings.¹

See also baseball slang for common slang that originated in baseball and baseball statistics for more formal definitions of some of the statistical concepts listed below.

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0–9

0-1 (i.e., "oh and one"), also, 1-0, 0-2, 1-1, 2-0, 1-2, 2-1, 3-0, 2-2, 3-1, 3-2: The possible instances of the "count", the number of balls and strikes, in that order, currently totaled for the batter. Japanese baseball reverses this. So 1-2 is 1 strike and 2 balls instead of 1 ball and 2 strikes.
1: 1 refers to the pitcher.
12-to-6: A curve ball, the motion of which evokes the hands of clock. The ball starts high (at "12-o'clock") and drops sharply as it reaches the strike zone ("6-o'clock"). Also known as "12-to-6 Downers" or a "12-to-6 Drop". Barry Zito is perhaps baseball's best current practitioner of the 12-to-6 curve.
2: 2 refers to the catcher.
3: 3 refers to the first baseman.
3-2-3 double play: A relatively rare combination resulting in a double play: With the bases loaded, the batter hits the ball to the first baseman, who relays it to home for the force out, who fires it back to the first baseman to retire the batter. Occurred very notably during Game 7 of the 1991 World Series, when catcher Brian Harper and first baseman Kent Hrbek of the Minnesota Twins turned a 3-2-3 against the Atlanta Braves; Lonnie Smith was prevented from scoring while Sid Bream was retired at first.
4: 4 refers to the second baseman.; In this instance 4 refers not to the second baseman (the 4 position), but to home plate, in essence the fourth base. This is typically used to signal that a runner is heading home and that the ball needs to be thrown to home plate.
5: 5 refers to the third baseman
6: 6 refers to the shortstop.
6-4-3 double play: A common combination resulting in a double play: A runner is on first base and a ground ball is batted to the shortstop (numbered 6 in scorekeeping). He throws to the second baseman (4) who steps on second base to force out the runner from first, then throws to the first baseman (3) standing on first base to force out the batter. A famous infield trio for the Chicago Cubs is remembered by this sequence: "Tinker to Evers to Chance." A similar combination is the 4-6-3 double play.
7: 7 refers to the leftfielder.
8: 8 refers to the centerfielder.
9: 9 refers to the rightfielder.

A

AA or A.A.: Abbreviation for American Association, the name of a major league of the 1880s and of a minor league for much of the 20th century. Also the abbreviation of the modern organization Alcoholics Anonymous, a possibly amusing coincidence in that the Association's critics (notably the rival National League) referred to the AA as "The Beer and Whiskey League".; "Double A" (AA) is also a minor league baseball level, and includes the Eastern League, the Southern League, and the Texas League.
AAA: "Triple A." The highest level of minor league baseball. Includes the Pacific Coast League, the International League, and the Mexican League.
AAAA player: A "4A player" is someone who is (repeatedly) very successful in the high minor leagues (the AAA level) but can't seem to to make it in the bigs. He's "too good" to remain in the minors but not good enough for the majors. He may bounce up and down between the minors and majors and never become an established major league player. This may be more due to mismanagement or bad luck than to his inability to play major league ball.
Air Mail: A very high overthrow in an attempt to make a play on a runner.
AL or A.L.: Abbreviation for American League, the newer of the two existing major leagues.
alley: The space between outfielders. A power hitter may hit the ball "up the alley" (the "power alley") or "in the gap," typically with the ball reaching the fence on a bounce. (If it hit the wall on the fly, it would be described as "off the wall," not "up the alley" or "in the gap".)
around the horn: a 5-4-3 double play, in which the ball goes from the third baseman, to the second baseman, who tags second, to the first baseman, who tags first. Like many baseball terms, this originates from sailing. Until the Panama Canal was built, the quickest way from the North Atlantic Ocean to the Pacific Ocean was to sail around Cape Horn, the southernmost tip of South America. By extension, "going around the horn" refers to covering all or several angles of something in baseball. More commonly, this phrase refers to the tradition of tossing the ball around the infield after an out is recorded such that no runners are left on base. For example, after an out recorded at first base, if there are no runners on, the first baseman will toss to the second baseman, and the ball will subsequently be thrown to the shortstop and then the third baseman, and finally back to the pitcher. The order in which the ball is thrown "around the horn," can vary from team to team and from situation to situation, but many teams see this as the "way" to do it and it may even be considered bad luck to deviate from this standard pattern. Also, some teams use this only when a strikeout is recorded. This version starts with the pitch being thrown and the last strike recorded then is quickly thrown from the catcher to the first baseman who proceeds with the regular order. Now it is used more as a method to show off, than to ensure that no runner is left on.
at bat (AB): 1. Colloquially, a batter is "at bat" or up to bat any time he's at the plate and in active play, attempting to hit the ball. 2. In baseball statistics, an at bat (AB) is counted only when the batter reaches first base on a hit or an error, is called out for any reason other than as part of a sacrifice bunt or sacrifice fly, or there is a fielder's choice. If the batter receives a walk, is hit by a pitch, or reaches first base because of catcher's interference, he is not charged with an "official AB." See "plate appearance" for further details.

B

backdoor breaking ball: A breaking ball thrown to the outside of the strike zone of a left-handed hitter by a right-handed pitcher, or to a right-handed batter by a left-handed pitcher. Since most breaking balls curve toward the batter in this configuration, a backdoor breaking ball appears to be a ball, on the outside, then curves sharply into the strike zone after the batter has given up on it, coming through the "back door" of the strike zone. A backdoor slider is a common version of this pitch, since the slider has more lateral motion than other pitches.
bad hop: a ball that bounces in front of an infielder in an unexpected way, usually because it hit some irregularity on the ground
balk: A ruling made by an umpire against a pitching motion that violates rules intended to prevent the pitcher from unfairly deceiving a baserunner. When a balk is called, each runner can freely advance one base. There are specific guidelines in the rules about what pitching movements are illegal. The spirit of a balk is that certain movements effectively "declare" the pitcher's intent to pitch to the batter, freeing the baserunner from any fear that he will be picked off. Some balks result from errant or unsuccessful motions, in the case of the ball accidentally slipping out of the pitcher's hand; this usage is likely linked to its use outside of baseball, to mean any process that has been prematurely blocked.
Baltimore chop: A short downward swing intended to make the ball rebound off the home plate or the packed dirt immediately in front of the plate. The goal is to produce a bounce high enough so that, even if it can be fielded by an infielder the batter will have time to reach first for a base hit. This was a tactic of the Baltimore Orioles of the National League in the 1890s, who frequently attempted this kind of hit purposely. John McGraw is supposed to have had the earth in front of home plate intentionally compacted for this purpose. When it happens in the modern game, and so named, it is more often simply a result of poor contact that just happens to aid the batter-runner.
bandbox: A ballpark with small dimensions that encourages offense, especially home runs.
banjo hitter: A batter who lacks power. A banjo hitter usually hits bloop singles, often just past the infield dirt, and would have a low slugging percentage. The name is said to come from the twanging sound of the bat at contact, like that of a banjo.
base hit: See "hit" or hit (baseball).
base knock: A single; a one-base hit.
bat around: A team is said to have "batted around" after each of the nine players in the lineup makes a plate appearance and the hitter who led off an inning returns for a second at-bat in that inning.
batter's background or batter's eye: A solid-colored, usually dark area beyond the center field wall that is the visual backdrop for the batter looking out at the pitcher. To allow the batter to see the pitched ball against a dark and uncluttered background, as much for the batter's safety as anything. The use of a batter's background has been standard in baseball (as well as cricket) since at least the late 1800s.; One example of a batter's background is the black area in center-field of Yankee Stadium. At one time, there were seats where the black area is now, but because of distractions the seats were removed and the area painted black.
batter's box: A rectangle on either side of the plate in which the batter must be standing for fair play to resume. Only a foot and a hand out of the box are required to stop fair play.
battery: The pitcher and catcher, speaking of them as a single unit. Henry Chadwick coined the term, drawing from the military sense of the term artillery battery. It also suggests a play on words, as the pitcher-catcher activities center on the batter.
batterymates: A pitcher and catcher from the same team.
batting average (BA): The average number of hits per at bat (BA=H/AB).
batting practice (also referred to as BP): The period before a game or at some other time when players warm up or practice their hitting technique. Sometimes the term is used to describe a period within a game when one team's hitters have so totally dominated a given pitcher that the game resembles a batting practice session.
beanball: A pitch intentionally thrown to hit the batter if he does not move out of the way, especially when directed at the head (or the "bean" in old-fashioned slang).
bench jockey: A player, coach or manager with the talent of annoying and distracting opposition players and umpires from his team's dugout with verbal repartee. Especially useful against those with rabbit ears.
bender: A curveball.
big fly: A long home run.
bigs: The big leagues, major leagues, "the show." If you're in the bigs you're a big leaguer, a major leaguer.
block the plate: A catcher who puts a foot, leg, or whole body between homeplate and a runner attempting to score, is said to "block the plate."
bloop: A weakly hit fly ball that drops in for a single between an infielder and an outfielder.
blowser: A closer who seems to get more blown saves than saves.
Blue: A term commonly used by players to refer to an umpire; referring to the typical umpire's uniform color, a dark blue; and usually when complaining about a call: "Oh, come on, Blue!"
bonehead play or just "boner": A mental mistake that changes the course of a game dramatically. See "Merkle boner".
bonus baseball: See "extra innings".
bottom of the inning: The second half of an inning, during which the home team bats, derived from its position in the line score.
box: The vicinity of the pitcher's mound. Baseball announcers will sometimes refer to a batted ball going back through the pitcher's mound area as having gone "back through the box", or a pitcher being removed from the game will be said to have been "knocked out of the box". In the early days of the game, there was no mound. The pitcher was required to release the ball while inside a box drawn on the ground. Even though the mound has replaced the box, this terminology still exists.
box score (baseball): The statistical summary of a game is reported in a box score. An abbreviated version of the box score, duplicated from the field scoreboard, is the line score. Invention of the box score is credited to Henry Chadwick.
BP: See "batting practice." (Devotees of baseball research also sometimes refer to Baseball Prospectus as BP.)
BR: Bats right; used in describing a player's statistics, for example: John Doe (TR, BR, 6', 172 lbs.)
breaking ball: Any pitch that markedly deviates from a "straight" path due to a spin used by the pitcher to achieve the desired affect.
bring: To pitch; "bring the gas", "bring the heat", "bring it".
brush-back: A pitch intentionally thrown close to a batter to intimidate or misdirect, i.e. to "brush him back" from the plate. Also purpose pitch. Also chin-music. A batter targeted by such a pitch is sometimes said to have had a "close shave". 1950s pitcher Sal Maglie was called "the Barber" due to his frequent use of such pitches.
bullpen: The area used by pitchers and/or catchers to warm up before taking the mound when standard play has already begun. This area is usually off to the side along either the left or right baseline, or behind an outfield fence. It is almost never in fair territory, presumably due to the risk of interference with live action. A rare exception was at the Polo Grounds, where the bullpens were in the deep left and right center field quarter-circles of the outfield wall. The term "bullpen" is also used to collectively refer to a team's relief pitching corps.
bunt: To bat the ball weakly and deliberately, by holding the bat nearly still and letting the ball hit it, trying to place the ball in a particular spot on the infield. Also, the play resulting from that action. Typically, a bunt is used to advance other runners and is then referred to as a "sacrifice". When done correctly, fielders have no play except, at best, to retire the batter-runner. Speedy runners also bunt for base hits when infielders are playing back.
bush league: A slang term used to describe play that is of inferior or unprofessional quality. The "bushes" or the "sticks" are small towns, the latter term also used in the acting profession, famously in the Variety headline of July 17, 1935, "Sticks nix hick pix", meaning small towns reject motion pictures about small towns.

C

Cactus League: The group of teams that conduct their pre-season spring training exhibition games in Arizona where the cactus grows in abundance.
can of corn: An easily-caught fly ball. Supposedly comes from a general store clerk reaching up and dropping a can from a high shelf. It may also be used in reference to acknowledging something or used when one is in mild excitement. Frequently used by Chicago White Sox broadcaster Ken "The Hawk" Harrelson.
catbird seat: A desirable or auspicious situation. Popularized by Red Barber, longtime broadcaster for the Brooklyn Dodgers. James Thurber wrote in his short story of the same title: "[S]itting in the catbird seat" means sitting pretty, like a batter with three balls and no strikes on him. The catbird is said to seek out the highest point in a tree to sing his song, so someone in the catbird seat is high up.
Change (or change up): a pitch meant to look like a fastball, but with less velocity; short for "change of pace".
chase after: To swing at a pitch well outside of the strike zone.
check the runner: When the pitcher looks in the direction of a runner on base, and thereby causes him to not take as large of a lead as he would otherwise have taken.
cheese: A fastball.
chin music: A high and tight, up and in pitch meant to knock a batter back from the plate in lieu of being hit on the chin. Also known as a brushback or purpose pitch.
choke up: Whereas an ordinary person might sometimes "choke up" with emotion and have a hard time speaking, a batter in baseball "chokes up" by sliding his hands up from the nub end of the bat to shorten his swing.
cleanup: The fourth batter for a team, usually a power hitter. The idea is to get some runners on base for the "cleanup" hitter to drive home.
climbing the ladder: a succession of pitches out of the strike zone, each higher than the last, in an attempt to get the batter to swing at a pitch 'in his eyes'
closer: A relief pitcher who is consistently used to "close" a game by getting the final outs. Closers are often among the most overpowering pitchers, and sometimes even the most erratic.
clutch: Good performance under pressure or when the chips are down/when good performance really matters (such a period is referred to as being "in the clutch.") May refer to a player (a good "clutch hitter") or to a team as a whole. For example, a player who hits many home runs but strikes out in crucial win-or-lose moments "can't hit in the clutch." The existence of "clutch" hitting is a controversial and divisive topic among baseball fans. All baseball fans agree that clutch hits exist, but there is significant disagreement over whether clutch hitting or being clutch is a skill a player can possess, i.e. whether his batting performance in the clutch is statistically or mathematically different from his overall batting performance, especially over the course of a career as opposed to a small portion of it.
collar: Symbol of going hitless in a game, suggested by its resemblance to a zero, along with the implication of "choking"; to wear the collar.
comebacker: a batted ball directly back to the pitcher
contact hitter: A hitter who does not strike out often. Thus, he's usually able to make contact with the ball and put it in play.
cornucopia: Texas Rangers TV announcer Bill Land once called an easily-caught fly ball in a game incorrectly by stating, "It's a cornucopia!" In the background, you could hear color-commentator, Tom Grieve mumbling "can..of..corn.."; See can of corn; It is not uncommon to hear fans in the lower rows of Section 15 at The Ballpark in Arlington yelling "CORNUCOPIA!"
covering: when a fielder goes to make a play at a base that is not his position (usually because the fielder for that base in unavailable to catch the ball at that base because he is busy fielding the batted ball. Most common example: 1st baseman catches a batted ground ball, but is too far from 1st base to put the runner out. The pitcher covers 1st base to take the throw from the 1st baseman.)
crooked number: A number greater than one, referring to the appearance of the actual number. A team which is able to score two or more runs in an inning is said to "hang" a crooked number on the scoreboard.
crowding the plate: When a batter comes extremely close to the plate, in essence covering up part of the strike zone, a practice that angers pitchers and, if done repeatedly, can lead to a bean ball being thrown at the batter to clear the plate.
cup of coffee: A short time spent by a minor league player at the major league level, the idea being that the player was only there long enough to have a cup of coffee.
curveball: A pitch that curves or breaks from a straight flight path toward home plate.
Cutter: a "cut fastball"; a fastball pitch that has lateral movement.
cut-off: Refers either to a cut-off man who shortens the throw or to cut off the ball. The phrase "hit the cut-off man" is a common phrase in baseball.
cut-off man: Specifically referring to the player that serves as a middle man in a throw to a far off and/or important target, such as: the shortstop or second baseman in a throw from deep center field to home plate or the shortstop in a throw from left field to the pitcher when a runner is on third base and it is important to not allow the runner to advance. The cut-off man does two things: it increases accuracy over long distances and serves to shorten the time the ball requires to get to a specific place. The latter is due to the fact that the ball, when thrown over long distances, loses a considerable amount of speed the farther it must be thrown.

D

Dead Ball Era: The time period prior to the Lively Ball Era, when the nature of the ball along with other rules tended to limit the power game, and the primary batting strategy was the inside game of baseball. Conventional wisdom says the Dead Ball Era ended after the 1919 season. Some have pointed out that the ball actually became livelier post-World War I, i.e. in 1919, but that teams did not significantly alter their "small ball" style of play until 1920 or later.
defensive indifference: A play in which a runner advances to the next base without a throw from the catcher or without any fielder attempting to cover the bag to accept a throw from the catcher. The runner then does not get credit for a stolen base because his action was not challenged in any way. This usually occurs in a game in which the score is heavily favored towards one team and a runner advancing a base will not make a large difference in the expected outcome of the game... specifically, the ninth inning with two outs, where the objective is simply to focus on the batter and induce him to make the final out.
Deuce: A curveball, because it is usually signalled for by the catcher by showing the pitcher 2 fingers. From the cardplaying term, where the "2" card is conventionally called the "deuce".
"Deuces wild": Term used to describe the occasion of a large quantity of the number "2" appearing on the scoreboard at the same time: 2 baserunners, 2 outs, 2 balls and 2 strike count on the batter. Derived from card-playing term, "deuces are wild", which is used in a different context in cards: the deuces (normally the lowest-ranking cards) are declared "wild cards"; their holder(s) can assign them any value that they think will give their hand(s) an advantage.
diamond: The layout of the four bases in the infield. The infield is actually a square 90 feet (27 m) on each side, but from the stands it resembles a parallelogram, or "diamond".
digging it out: Fielding a ball on or near the ground. Usually a 1st baseman taking a low throw from another infielder
dinger: Home run. Also homer, round-tripper. See more nicknames in the article home run.
dish: 1. Referring to home plate, e.g., "The batter is 1-3 at the dish." 2. A good pitcher can really dish the ball -- get it over the plate. An announcer may say "Here comes the dish" (the pitch), or "He's really dishing it tonight."
doctoring the ball: Cheating by applying a foreign substance to the ball, or otherwise altering it, to put an unnatural spin on a pitch. Examples: Vaseline or K-Y or saliva ("spitball") possibly aided by chewing slippery elm; or scuffing with sandpaper, emory board or belt buckle. All of these became illegal beginning in the 1920 season.
double: A two-base hit. See "hit" and double (baseball).
double header or doubleheader: When two games are played back-to-back by the same two teams on the same day. In the major leagues, both games are scheduled for 9 innings. In amateur leagues or minor leagues, the second game may be scheduled for only 7 instead of 9 innings. When the games are scheduled for late in the day, they are referred to as a "twilight-night" or "twi-night" doubleheader. When one game is scheduled for the afternoon and one for the evening (typically with separate admission fees), it is referred to as a "day-night" doubleheader. The doubleheader is baseball's equivalent to the movie "double feature". The separate admission charge for so-called "day-night" doubleheaders belies the original "two for the price of one" concept of the doubleheader.
double play: Any sequence of defensive plays in the same continuous playing action resulting in two outs. Hence:
double play depth: 2nd baseman and shortstop play further back on the infield than standard depth, but on a narrower arc so that any ball hit up the middle will allow for one middle infielder to reach the ball quickly and the other to reach the base fast enough to force the out at second and thow to first in the same motion. This set forces the third baseman further toward second and closer in than his normal set. Because of the increase in size of the third base and right field gaps, pitches in this defensive set will tend to be straight down against right handed hitters and down and toward the outside against lefties, increasing the likelihood of a batted ball grounding toward the middle infield arc.
down the line: On the field near the foul lines, often used to describe the location of batted balls.
down the middle: Over the middle portion of home plate, used to describe the location of pitches. Also referred to as "down the pipe", "down Main Street", "down Broadway", etc. "Down Peachtree" in Atlanta in reference to the long street through the middle of the city.
drop ball: When a pitch suddenly drops as it approaches home plate, also known as a "sinker." Some extreme "12-to-6" curveballs are also referred to as "drop balls," since they start high and dive as they reach the plate. Also known as a "dropper" or "el droppo".
drop off the table: When a pitched ball (e.g., a curveball) breaks extremely sharply.
duck snort: (Also known as a duck fart) A softly hit ball that goes over the infielders and lands in the short outfield for a hit. Origin - The term originates from "duck fart" becasuse the hit was very soft. Because ducks have feathers it is assumed that their farts are very soft (quiet).
ducks on the pond: runners on base, especially when the bases are loaded: "Look at all the ducks on the pond!"
duster, dust-off pitch: A pitch that is thrown so close to a batter that he drops to the ground ("hits the dust") to avoid it. Somewhat contradictorily, on the same play the pitcher may be said to have "dusted off" the hitter.
dying quail: A batted ball that drops in front of the outfielders, often unexpectedly (like a shot bird).

E

Eephus: A very slow pitch with a high arcing trajectory. Invented by 1930s Pittsburgh Pirates hurler Rip Sewell, it is not a part of any current pitcher's repertoire, but some (Orlando Hernandez has a variation) do throw it occasionally to fool a hitter's timing. Prior to the 1946 All-Star Game, Sewell boasted that the Eephus had never been hit for a home run; during that very game, Ted Williams famously proceeded to rip the ball out of his home park, the only time anyone would ever homer off the Eephus.
early innings: The first, second and third innings of a regulation nine-inning game.
earned run: any run for which the pitcher is held accountable (i.e., the run did not score as a result of a fielding error or a passed ball).
earned run average (ERA): the average number of earned runs allowed by a pitcher per 9 innings pitched.
excuse me swing: When a batter inadvertently makes contact during a check swing. Contrast with swinging bunt.
extra bases: Any bases gained by a batter beyond first base on a hit. Doubles, triples and home runs are referred to as "extra base hits."
extra innings: Additional innings needed to complete a game which is tied at the end of the regulation number of innings, typically 9 (nearly all levels of the sport), possibly 7 such as in the second game of a doubleheader (minor or amateur leagues only). Also known as "bonus baseball", "bonus cantos" or "free baseball", in that paying spectators are witnessing more action than normal.

F

fan: A strong supporter of a player, a team, or the game in general. As Paul Dickson explains, this term originated in the sport of boxing. Those who followed or "fancied" boxing in the 19th century were called "the fancy". The segment of the public that followed boxing tended to also follow baseball. "The fancy" was shortened to "the fans", was adopted into baseball (replacing the 19th century term "kranks" or "cranks"), and was reinforced by its apparent connection to the word "fanatics."; Additionally, to "fan" a batter is to strike him out, especially a swinging strike 3.
fielder's choice (FC): A fielder's choice is most often the act of a fielder, upon fielding a batted ball, choosing to try to put out one runner while in so doing allowing the batter-runner to advance to first base. In statistics, despite reaching first base safely after hitting the ball, the batter would not be credited with a hit (H) but would be charged with an at bat (AB).
figger filbert: An old-fashioned and funnier way of saying "numbers nut", for a fan with a near-obsessive interest in the stats or "figures" of the game. Bill James could be said to be the iconic "figger filbert".
fireballer: A fastball pitcher who throws smoke, a bullet, a heater (you can feel the heat generated by the ball), or a hummer (you can't see the ball but you can hear it go past you).
fireman: A team's top relief pitcher, brought in to end a rally 'put out the fire'.
FL or F.L.: Abbreviation for Federal League, a major league that existed for two years, 1914-1915.
fly ball: A ball hit high in the air, as opposed to a ground ball.
force play, forced out: When a runner must advance and tagging him is not required and stepping on the base with the ball in hand will suffice. First base is always a forced out, the remaining bases become forced outs when more than one runner is on base and must advance such as when a runner is on first and must run to second when the ball is hit right to the second baseman or shortstop forcing the out.
fouling off: Batting a pitch foul with two strikes, in order to keep the at bat going, in part to help wear down the pitcher. Luke Appling was said to be the king of fouling them off.
free baseball: Another term for extra innings.
frozen rope: a hard hit line drive (travels in a straight line)
full count: A count of 3 balls and 2 strikes; that is, no more balls or strikes can occur without a result.
fungo: a ball hit mainly for practice by a player tossing the ball in the air and then hitting it.
fungo bat: a lightweight bat with a triangular or flat barrel used to hit fungoes.

G

gap: The space between outfielders. See "alley."
gas: A fastball, a pitcher's fastest pitch, "Give him (the batter) the gas"; as in stepping on the gas pedal in a car and accelerating.
general manager (GM): The person who runs the baseball organization (personnel, finance, operations). Not the manager on the field ("the manager"), and not the owner of the club.
Get on one's horse: When a player (usually an outfielder) runs extremely fast towards a hard hit ball in an effort to catch it.
Getting off the schneid: To break a scoreless or hitless or winless streak (i.e. a schneid). According to the Dickson Baseball Dictionary, the term "schneid" comes to baseball via gin rummy, and in turn comes from German / Yiddish "schneider," one who cuts cloth, i.e., a tailor.
GIDP: Grounded into double play.
GM: See "general manager."
Going Yard: To "go yard" is to hit a home run.
Golden Sombrero: One who strikes out four times in one game is said to have gotten the Golden Sombrero.
golfing: Swinging at a pitch obviously outside of the strike zone, particularly one pitched low or in the dirt. Also, golfing can be used to describe actual contact with a pitch low in the zone (he golfed that one for a home run). Vladimir Guerrero and Alfonso Soriano are "golfers" par excellence.
Good hit, no field: Said to have been the world's shortest scouting report, and often quoted in reference to sluggers such as Dick Stuart and Dave Kingman, who were notoriously poor fielders.
good wood: A batter who gets "good wood on the ball" or who "gets some lumber" on the ball hits it hard.
Grapefruit League: The group of teams that conduct their pre-season exhibition games in Florida, where citrus fruit trees grow in abundance.
green light: In a situation where a hitter will typically be taking a pitch, such as on a 3-0 count, if the hitter is given permission to swing away, he is said to be given the green light.
ground ball: A ball hit on the ground, i.e. bouncing repeatedly in the infield.
ground ball with eyes: A ground ball which barely gets between two infielders for a base hit, as if it could "see" the only spot where it would be unfieldable.
Ground rules: Rules that are specific to a particular baseball ground, i.e. a ballpark, due to unique features of the park and where the standard baseball rules may be inadequate. An obvious example is a batted ball lodging in the ivy at Wrigley Field, upon which play is stopped and all runners are awarded two bases, hence the batter is said to have achieved a "ground rule double".

H

hanging curve: A curveball that does not drop very much in its delivery, especially when hit for a home run.
hard hands: a fielding defect - balls tend to bounce out of the fielding player's hands.
hat trick: To strike out three times. Used jokingly, as the same term means to score three times in hockey and other sports.
HBP: hit by pitch
heat: A fastball, a pitcher's fastest pitch, as in "Bring the heat".
high and tight: High, or above the strike zone, and close to the batter, used to describe the location of pitches.
high cheese: A strike thrown in the high strike zone.
high, hard one: a fastball thrown high in the strike zone or above the strike zone.
high heat: A "rising" fastball, which can be very difficult to hit; with two strikes on the batter, the pitcher might "bring the high heat" and go for the K. Also known as "high cheese". Not to be confused with the baseball PC game of the same name, published by 3DO.
hill: Referring to the pitcher's mound.
hit (H), base hit: The act of safely reaching first base, or any other base after batting the ball into fair territory. See hit (baseball) for details, including the fielder's choice exception to this definition.; The term "hit" includes both singles and "extra base hits." A hit in which the batter reaches only first base on the play is called a single or a one-base hit or simply a base hit. A hit in which the batter reaches second base on the play, and there has been no fielding error, is called a "double" or two-base hit. A hit in which the batter reaches third base on the play and there has been no fielding error is called a "triple" or three-base hit. A hit in which a batter reaches home plate on the play and there has been no fielding error is called a "home run."; "Raffy had three hits today, two for extra bases. He singled in the first, tripled in the 3rd, and hit a home run in the 8th."
hit and run: Offensive play executed jointly by a baserunner (usually on first base) and batter. At the pitch, the baserunner begins to run towards second as if to steal the base. One of the two middle infielders must move towards second base to catch the catcher's throw and attempt to tag out the runner. The batter attempts to hit the ball into the gap or "hole" vacated by the middle infielder (so contrary to the name, the hit follows the run). A successful hit and run can avoid a double play and advance the first-base runner to third. The hit and run is usually ordered, or put on, by the manager.
hit 'em where they ain't: Said to be the (grammatically-casual) response of late-19th-century / early-20th-century player Willie Keeler to the question, "What's the secret to hitting?" in which "'em" or "them" are the batted balls, and "they" are the fielders.
hit for the cycle: To hit a single, double, triple and home run in the same game. To accomplish this feat in order is termed a "natural cycle."
hit the ball on the screws (or on the button): To strike the ball solidly, not necessarily to get a hit or to knock it out of the park. A batter who is down on his luck may be content to know that at least he hit the ball on the screws and put it into play. He's also happier when he hits the ball on the button.
hitting behind the runner: To intentionally put the ball in play to the right side of the field with a runner on second and less than two outs, with the intent of advancing the baserunner to third base, where a sacrifice fly by the next hitter can result in a run.
hole in his glove: a tendency to drop caught balls.
hole in his swing: location in or near the strikezone where the batter can't hit a pitch
homer: A home run, which is when the ball is hit over the outfield fence in fair play.; Also, a dedicated fan (often a team broadcast announcer) who vehemently supports all of a team's players, decisions, and chances of winning, despite any contrary evidence.
homestand: When a team returns to its home baseball park to play several games it makes or plays a homestand. A homestand typically involves several "home games," after which the team "goes on the road" and plays "road games" at other stadiums.
hook foul: When the batter "pulls" the ball down the line, starting fair and ending foul, on the same side of the diamond that the batter is standing. Contrast with slice foul. Both terms are also used in the game of golf.
hot box: Same as rundown or, specifically, the area occupied by the runner while he is being "run down".
hot corner: The third base fielding position, so called because many batted balls arrive very quickly at the position.

I

throwing in the batter's eyes: pitching a high fastball, usually at or near the batter's eye level. A "ball", and hard to hit, but hard to lay off.
infield fly: A call made by the umpire signaling the batter is out when he hits a fly ball that can be caught by an infielder with runners on first and second or with the bases loaded and less than two outs. This rule is intended to prevent the fielder from intentionally dropping the ball and getting force outs on any or all of the runners on base. The rule is sometimes a little mystifying to casual fans of the game, but it has been a fundamental rule since 1895, presumably to prevent the notoriously tricky Baltimore Orioles from doing it.
inside baseball or inside game: Playing strategy that focuses on teamwork and good execution. It is a double-meaning term in that such strategy usually centers around the infield - the walk, the base hit, the bunt, the stolen base, etc. The last of the ninth inning in Game 4 of the 2004 ALCS is a perfect example: a walk, a steal and a single to tie the game. The game was tied by the inside game, but was won by the power game, in extra innings, when slugger David Ortiz hit a walk off home run. The inside game was the primary approach to playing baseball during the Dead Ball Era. "Inside baseball" is commonly used as a metaphor in American politics to describe background machinations that have no relevance to anyone not working in politics.^{[citation needed]}
insurance run: When a team is leading the game by a run or two, it hopes to get an "insurance run" to provide a margin of safety in the late innings of the game.
intentional walk: When a pitcher throws pitches well outside of the strike zone in order to walk a batter, rather than give him a chance to get a potentially more damaging hit. Usually, the catcher will take a step or two away from the batter to minimize the chance of the pitch drifting into the hittable area. Often an intentional walk will occur with "first base open," meaning there is a runner on second or third, but none on first, since then the walk doesn't dramatically benefit the offense, and opens the possibility of a double play. An intentional walk is seen as both a compliment to the batter being walked, and an insult to the following batter, whose batting skills are being disregarded. There is also a term, "unintentional intentional walk," which refers to an intentional walk given by throwing pitches in the vicinity of the strike zone, hoping to get the batter to chase one, but without any real attempt at getting him out. This is also called "pitching around" the batter.
in the hole (1): On the infield at a location nearly exactly between fielders, used to describe the location of a batted ground ball, or the location a fielder as he runs to try to retrieve that ball. Used most often in reference to the space between the first and second basemen, or between the shortstop and the third baseman. A ground ball hit between second and short is more apt to be described as "up the middle". The term is also occasionally used to designate the space between any pair or group of fielders. In any case, "the hole" is "where they ain't" as Willie Keeler famously stated. Term similarly used in football.
in the hole (2): Due to bat third in order; batting immediately after the on-deck batter. Presumably derived from card-playing terminology, or perhaps from boating, where it was originally "in the hold" - the place prior to being "on deck!"
in play: See "put the ball in play."

J

Jack: A Home Run, as in, "Hitting a jack" or "Jacking one out of here"
jam: As a verb, to throw a pitch far enough inside that the batter is unlikely to make good contact if he hits it. "The pitcher jammed the batter". As a noun, a situation where there are runners on base in scoring position, 1 or none out, and good hitters coming up. "The pitcher is in a jam."
Junior Circuit: The American League, so-called because it is the younger of the two major leagues.
junk: a sequence of several different pitches with not much velocity but a lot of movement. Throwing junk is usually a strategy of a pitcher who does not have a good fastball.
junkball pitcher: a pitcher who throws predominantly off-speed pitches.

K

K: Strikeout. A backwards K is sometimes used to denote a strikeout looking and forwards to indicate a strikeout swinging. Originating from the last letter of "struck" (as per Henry Chadwick, inventor of baseball scorekeeping techniques) and reinforced by inference of "knockout" or "K.O."
keep the line moving: reference to a series of batters reaching base, alluding to an assembly line
keystone sack: Second base. Like the keystone of an arch, second base is "key" to both scoring (a runner on the base is in "scoring position") and preventing scoring (by defensive "strength up the middle").
knocks: 1. A player who "knocks in 3" gets three RBI's. 2. Sometimes a player is simply praised for getting some "solid knocks" (perhaps extra-base hits) but not necessarily any RBI's. 3. A "one-base knock" is a single, a "two-base knock" is a double. Presumably the "knocks" are the sounds of the ball hitting the wooden bat.
knuckleball: A pitch that is thrown with the knuckles and/or the fingernails. It tends to flutter and move suddenly as it is on its way to the plate. Often, knuckleballs have very little or no spin at all. Can also refer to a batted ball, typically a line drive that appears to flutter in flight.

L

late innings: The seventh, eighth and ninth innings of a regulation nine-inning game.
Lawrence Welk: a 1-2-3 double play (and a one, ana 2, ana 3...)
lead off (base running): When a base runner steps off of the base in order to reduce the distance to the next base, before a pitch is thrown.
lead off (batting order): The player who is first in the batting order for a given team. Also, the first batter in any given inning.
leather: Referring to a fielder's glove, a player with "good leather" is a good defensive player (typically an infielder).
left on base (LOB): The number of runners left on the basepaths after the third out is made. Published Box scores usually include LOB totals for each team as a game statistic, and often include LOB totals for each hitter in the lineup.
lineup: the batting order
lineup card: a scorecard kept by the manager of each team on which all players who enter a game for any reason must be listed showing their place in the batting order
Lively Ball Era: The time starting around 1919 (many say 1920) when several factors came together to shift baseball away from the time-honored inside game to the power game, ending the Dead Ball Era. Following World War I, the construction of the baseball improved significantly, with a cork center and tighter-wound yarns that made the ball inherently "livelier". Also, there were significant rules changes that abolished abuse of the ball (such as the spitball) and also required substitution of a new ball when the previous ball became dirty or scuffed. This gave a great advantage to hitters, especially power hitters. Babe Ruth and Rogers Hornsby were most notable among those who took full advantage of these changes and rewrote the record books.
load the bases: A succession of plays that results in base runners occupying first, second, and third bases.
lollipop: a soft straight pitch with a lot of arc
long ball: A home run. A team may be said to "win by the long ball" if a player hits a game-winning home run or the team hits several home runs to gain a win.

M

meatball: an easy pitch to hit - down the middle of the plate
Mendoza line: A batting average of .200. Batters hitting below .200 are colloquially said to be below the Mendoza line. Named for Mario Mendoza, a notoriously poor hitter of the 1970s. Less commonly used for .215, Mendoza's lifetime batting average. See this site for more.
men in blue: The umpires.
Merkle Boner: Refers to Fred Merkle's infamous baserunning gaffe that cost the Giants the 1908 pennant, but can be used to describe any mental error that costs a team the game. A good example would be forgetting the number of outs and tossing the ball into the stands, allowing the runners to advance.
middle infielders: The second baseman and shortstop.
middle innings: The fourth, fifth and sixth innings of a regulation nine-inning game.
middle of the inning: The few minutes that lapse between the top and bottom half of an inning when the visiting team takes the field to defend, and the home team prepares to bat. No gameplay occurs during this period. Television and radio broadcasts run commercial breaks during the middle of an inning. See also seventh-inning stretch.
Moneyball: An often misused term. It refers to the 2002 book of the same name, written by Michael Lewis. "Moneyball players" are most often referred to those who walk a lot, have high on-base percentages, and don't steal a lot of bases. However, the essense of the book is about running an organization effectively by identifying inefficiencies and finding undervalued assets in a given market. As an example. the so called Moneyball teams have shifted their focus to defense and speed instead of OBP which is no longer undervalued. "Moneyball" is often seen as the antithesis of "smallball", where teams take chances on the basepaths in an attempt to "manufacture" runs. In more traditional baseball circles, evoking Moneyball to describe a player or team can be a term of derision.
mop up: A mop-up pitcher comes in after the outcome of the game is all but certain. Sometimes other position players also come in to mop up in the last inning, and give the starters or regulars a rest.
movement: Refers to deviations from a straight flight of a pitch. More movement is preferable because it makes the ball harder to hit. Can be used to refer to both straight pitches (fastballs) and curving pitches (breaking balls). Movement in a fastball only occurs at higher speeds (over 80 m.p.h). If you watch such a pitch up close, it appears to "bounce" on the way, much like turbulence on an airplane. Hence the term "rising fastball".

N

NA or N.A.: Abbreviation for National Association. It could mean the long-ago amateur organization called the National Association of Base Ball Players; or the first professional league, called the National Association of Professional Base Ball Players; or the modern collective governing body of those minor leagues that are affiliated with the major leagues, long called the National Association of Professional Baseball Leagues (also abbreviated NAPBL) and officially renamed "Minor League Baseball" in 1999 [1].
NL or N.L.: Abbreviation for National League, the older of the two existing major leagues.
no-hitter: A game in which a team is held hitless by the opposing pitcher(s). Also given the childlike nickname "No-No". If no batter reaches base by any means at all (walk, error, etc.) the pitcher is said to have pitched a "Perfect Game".
nubber: A batted ball that doesn't travel very far, usually at low speed. It is often the result of hitting the ball on the end of the bat (ie - the fat part of the bat).

O

Ofer: A player who goes hitless in a game, or wears the collar, as in "0 for 4" (spoken as "oh for four") or however many at bats he took in the game.
Olympic Rings: Used when a player strikes out five times in a game.
On base percentage (OBP): Percentage of the time that a batter gets on base for any reason other than a fielding error or a fielder's choice.
on-deck: The next batter due to bat, after the current batter; the second batter in order. The designated area for the on-deck batter is a circle 5 feet (1.5 m) in diameter, officially called the "next batter's box", and commonly called the "on-deck circle". Ironically, the on-deck batter rarely steps or stands on the on-deck circle.
"Onion": Derisive nickname of the short-lived Union Association.
on the black: A pitch which is over the outside or inside, black edge of home plate.
one-hitter: A game in which one of the teams was limited to only one base hit, typically thought to be an extraordinary pitching performance. Other batters can reach base via walks, errors, or being hit by a pitch, but only one can reach base through a base-hit.
OPS: On-base plus slugging. A recent term invented by "statheads" that is said to be a good measure of a player's ability to produce runs for his team.
outside corner: Over the edge of home plate away from the batter, used to describe the location of pitches.

P

to paint: to throw the ball at the edges of the strike zone. A pitcher who has so much control that he can paint regularly may be referred to as Rembrandt or Picasso. Or he can be said to "paint the black" (the black edges of the plate).
park: To hit a home run. He parked a three-run homer. Also see yard
payoff pitch: A pitch made when the pitch count is full, i.e., when three balls and two strikes have been totaled for the batter. The implication is that much effort has gone into reaching this point (this is at least the sixth pitch of the at bat), and the pitch will either pay off for the pitcher (resulting in a strikeout) or the batter (resulting in a hit or a walk). This is not always so, though, as a foul would extend the length of the at bat. The term is most often used when whatever happens next will either score a run or end the inning.
PCL: Pacific Coast League -- a class AAA baseball league (AAA minor league).
pea: A pitched ball thrown at high speed. "Clem can really fling that pea."
PECOTA: A system for forecasting pitcher and hitter performance developed by Nate Silver of Baseball Prospectus. A player's "PECOTA" may be the forecasted range of his performance on a variety of indicators for the current or future seasons.
perfect game: A special type of no-hitter, in which the pitcher (or pitchers) retire each batter consecutively, allowing no baserunners via base on balls, error, or any other means. Although a perfect game could involve multiple pitchers (one pitcher relieving another for whatever reason), this has never happened in major league baseball. The list of perfect games is very short, and all of them were complete games by a single pitcher.
pickle: Same as rundown.
pickoff: A quick throw from the pitcher to a fielder covering a base, with the intention of catching the runner off-base. It may also serve to keep the runner's lead in check. The pitcher must either first step off the pitching rubber with his push-off foot, or clearly step towards the base he is throwing at with his lifted leg, in order for the move to not be ruled a balk. The catcher may also sometimes make a pickoff throw if a runner has strayed too far off-base after a pitch is thrown.
pinch hitter: A hitter substituted, mid-inning, for the scheduled batter. Often, a pinch hitter is brought in during a critical situation (a "pinch", or "the clutch") to replace a weak batter (usually the pitcher, in the National League). Although that's the origin of the term, any batter substituting for another, for any reason, is conventionally called a pinch hitter.
pinch runner: A runner substituted for another runner who is on base. Often, a pinch runner is brought in during a critical situation (just as with a pinch hitter), typically to replace a slower runner with a faster runner in hopes of gaining an extra base. However, any substitute runner, for whatever reason, is conventionally called a pinch runner.
pitch: When the baseball is thrown by the pitcher from the pitching mound to the catcher in standard play.
pitcher: The player responsible for pitching the ball. Known as the "1" position.
pitch around: not intentionally walking a batter, but not throwing him a hittable pitch - hoping to get him to swing at bad pitches
pitch count: The total number of pitches a pitcher has thrown in a given game.
pitch out: A pitch that is so far outside that it can't be hit. The catcher catches the pitch while standing, allowing a quick throw to try picking off a runner.
PL or P.L.: Abbreviation for Players' League, a one-year (1890) major league.
Platinum Sombrero: A batter who strikes out five times in one game is said to have gotten the Platinum Sombrero
player to be named later: When two baseball clubs make a trade, part of the publicly announced deal may involve an unspecified "player to be named later" who is not one of the headline players in the deal.
playing in: see double play depth. Also can refer to the 1st baseman and/or 3rd baseman playing closer to home plate in anticipation of fielding a bunt.
position player: A non-pitcher.
power hitter: A powerful batter who hits many home runs and extra base hits, but who may not have a high batting average, due to an "all or nothing" hitting approach. Also slugger.
pull hitter: Any batter that can "pull hit," a technique where the batter hits the ball towards their side of the field (i.e. a right handed hitter would pull hit to the left because they bat on the left side of the plate). This is a difficult thing to do because the tendency is to hit towards the opposite side of the field.
pull the string: To throw a pitch which breaks hard and late, exclusively in a strikeout situation, usually when the count is full. A pitcher has only 'pulled the string' if he successfully fools the batter into swinging where the pitch was going, not where it ends up, therefore striking him out. The image is of a marionette jerking to one direction as a string is pulled hard.
punch-out: A strike-out. Perhaps borrowed from boxing, just like the K (or K.O.). Also used as a verb, "Clem punched him out."
purpose pitch: See "brushback."
put the ball in play: To hit the ball in fair territory where it may go for a hit or a defensive player may make a play on the ball (try to catch or field it). Taking a walk (or being hit by a pitch), striking out, or hitting a home run over the fence are not putting the ball into play.

Q

quality start: A starting pitcher is credited with a quality start if he lasts at least 6 innings and holds the opponents to 3 or fewer earned runs.
quick pitch: When the pitcher comes to a less-than-complete stop in the midst of the stretch position, in an attempt to throw off the timing of batter and runners. When detected, the umpire calls the pitch a balk, and all runners can freely advance one base.

R

rabbit ears: A player who becomes nervous or chokes when opposing players or fans yell at or razz him is said to have "rabbit ears."
rainbow: usually a curve ball with a high arc in its path to the plate
rally cap: When fans or players wear their caps backwards, sideways, or inside-out to bring good luck to their team in hopes that it will "rally" to win the game. Said to have originated during the 1986 World Series when the New York Mets were losing the 6th game to the RedSox and were down 2-3 in the series; in the 7th inning, the Mets players all started wearing their caps inside out while sitting in the dugout, and the team rallied to win the game and the series.
range: the extent of a fielder's ability to move from his position in time to reach and field a ball in play.
RBI: run batted in; a run in baseball that is driven in by a batter. Also: official credit to a batter for driving in a run.
relay: the process of getting the ball from the deep outfield to third base or home plate by first throwing to an infielder, who then throws to the final target. The relay to the plate...he's out at home!
reliever or relief pitcher: A pitcher brought in the game to replace (i.e. "relieve") another pitcher.
rhubarb: an argument or fight in a baseball game. Hence, Rhubarb, a novel by H. Allen Smith.
ribbie: Expansion of the initial's RBI, which stand for Run batted in
ring him up: Another term for a strikeout.
RISP: See runners in scoring position.
rope: A hard line drive. Also see "frozen rope."
rubber arm: A pitcher is said to have a "rubber arm" if he can throw many pitches without tiring. Livan Hernandez may have the ultimate rubber arm, having eclipsed 200 innings seven times in his ten-year career.
rubber game or rubber match: term used for the third game of 3-game series, the fifth of a best-of-five series, and the seventh of a best-of-seven series, when the two teams have split the first two, four, or six games, respectively. Originally a card-playing term. (Ask Yahoo!).
rundown: A play in which a runner is stranded between two bases, and runs back and forth to try to avoid fielders with the ball. The fielders (usually basemen) toss the ball back and forth, to prevent the runner from getting to a base, and typically close in on him and tag him, barring an error or the need to make a play on another runner. Also called a hot box or a pickle. Sometimes used as a baserunning strategy by a trailing runner, to distract the fielders and allow a leading runner or runners to advance.
runners at the corners: runners on 1st and 3rd, with 2nd base open.
runners in scoring position (RISP): See "scoring position." RISP is also a statistic used to assess the efficiency or the effectiveness of a team's hitters. Good hitters typically have higher batting averages when there are RISP.
Ruthian Blast: A home run that travels very far.

S

sacrifice bunt: a sacrifice bunt (also called a sacrifice hit or simply a "sacrifice") is the act of deliberately bunting the ball in a manner that allows a runner on base to advance to another base, while the batter is himself put out. If the sacrifice is successful, the batter is not charged with an at bat (AB). But he is credited with a SAC or S or SH.
sacrifice fly (abbreviated as SF).: When a batter hits a fly ball to the outfield which is caught for an out, but a runner scores from 3rd base after tagging up or touching the bag following the catch. The batter thus "sacrifices" himself, gets credited with an RBI, but is not charged with an at bat (AB).
safety squeeze: a squeeze play in which the runner on third waits for the batter to lay down a successful bunt before breaking for home. Contrast this with the suicide squeeze.
screwball: A pitch that curves to the same side as the side it was thrown from. For a right-hand pitcher, the ball would break to the right -- it would break "in" to a right-hand hitter.; SYNONYMS: reverse curve, fadeaway, fader, screwgie, scroogie, reverse curveball
salad: an easily handled pitch.
Sally League: The South Atlantic League, a AA minor baseball league with teams located mainly in the southeastern United States.
scoring position: a runner on 2nd or 3rd base is in scoring position.
seamer

2 seamer - a "two seam fastball" where the ball is held by the pitcher such that, when thrown, its rotation only shows two seams per revolution
4 seamer - like a 2 seamer, but the rotation shows 4 seams per revolution of the ball. Batters count the number of visible seams to help judge what kind of pitch by its rotation.

seeing eye ball: a batted ground ball that just eludes capture by an infielder, just out of infielder's range, as if it could "see" where it needed to go. Less commonly used for a ball that takes an unusual lateral bounce to elude an infielder
Senior Circuit: The National League, so-called because it is the older of the two major leagues.
setup man: A relief pitcher who is consistently used immediately before the closer.
seventh-inning stretch: The period between the top and bottom of the seventh inning, when the fans present traditionally stand up to stretch their legs. A sing-along of the song "Take Me Out to the Ball Game" has become part of this tradition, a practice most associated with Chicago broadcaster Harry Caray. Since the September 11, 2001 attacks in the United States, "God Bless America" is sometimes played in addition to, or in lieu of, "Take Me Out to the Ball Game" in remembrance of those who lost their lives in the attacks, especially at home games of the New York Yankees and New York Mets. This occurs on Opening Day, Memorial Day, July 4th, Labor Day, September 11th, Sundays and during the All-Star Game, and post-season including the World Series.
shade: verb, where a player(s) (usually an outfielder) positions oneself slightly away from their normal spot in the field based on a prediction of where the batter might hit the ball.
shift: where the entire infield and/or outfield (that is, the players) position themselves clockwise or counter-clockwise from their usual position. This is to anticipate a batted ball from a batter who tends to hit to one side of the field. Also shade. In the case of some batters, especially lefthanders, and with the bases empty, managers have been known to shift fielders from the left side to the right side. This was done to Willie McCovey among others. The most extreme case was the famous "Ted Williams shift" (also once called the "Lou Boudreau shift"). Cleveland Indians manager Boudreau moved 6 of 7 fielders (including himself, the shortstop) to the right of second base, leaving just the leftfielder playing shallow, and daring Teddy Ballgame to single to left rather than trying to "hit it where they ain't" somewhere on the right side. Williams saw it as a challenge, a game within The Game, and seldom hit the ball to left on purpose in that circumstance.
shoestring catch: When a fielder, usually an outfielder, catches a ball just before it hits the ground ("off his shoetops"), and remains running while doing so.
shoot the cripple: when the pitch count is 3 balls and no strikes, the pitcher is presumed to need to pitch inside in order to obtain a strike. The name comes from the belief that the next pitch will be easy to hit; since the pitcher has to throw a strike in order to pull close in the count, getting a hit will be as easy as "shooting a cripple".
short hop: a ball that hits the ground immediately in front of an infielder.
the Show: the major leagues. Particularly "in the Show." Or in "the Bigs" (big leagues, major leagues).
shuts the door: Term used to describe when a pitcher, generally the closer, finishes the ballgame with a save.
sinker: A pitch, typically a fastball, that breaks sharply downward as it crosses the plate. Also see "drop ball."
slice foul: When a fly ball or line drive starts out over fair territory, then curves into foul territory due to aerodynamic force caused by spinning of the ball, imparted by the bat. A slice curves away from the batter (ie: it curves to the right for a right-handed batter and to the left for a left-handed batter).
slide: A slide is when a player drops to the ground when going into a base, to avoid a tag and (in the case of second or third base) as a means of stopping, so as not to overrun the base and risk being put out. Players also sometimes slide head-first into first base, thinking it will get them there faster than simply running.
slider: A relatively fast pitch with a slight curve in the opposite direction of the throwing arm.
slug: To hit with great power.
slugger: Any person who commonly hits with great power, but sometimes used in reference to a child to boost their ego.
slugging average, often abbreviated as SLG or SA: a measure of the power of a hitter, calculated as total bases divided by at bats.
small ball: A strategy by which teams attempt to score runs using station-to-station, bunting and sacrifice plays; usually used in a situation where one run will either tie or win the game; "manufacturing" run(s); close kin to inside baseball.
smoke: A pitcher who "throws smoke" throws it so hard that the batter is likely only to see the ball's smoke trail.
smoked: When a play-by-play reporter exclaims "That ball was smoked!" he implies that it was hit so hard that all you could see of the ball is its smoke trail.
soft hands: A fielder's ability to cradle the ball well in his glove. Contrast hard hands.
sophomore jinx: The tendency for players to follow a good rookie season with a less-spectacular one. (This term is used outside the realm of baseball as well.) Two of the most notorious examples are Joe Charboneau and Mark Fidrych. The statistical term for the sophomore jinx is "regression to the mean".
southpaw: Left-hander, especially a pitcher. Most baseball stadiums are built so that home plate is in the west and the outfield is in the east, so that when the sun sets it is not in the batter's eye. Because of this, a left-handed pitcher's arm is always facing south when he faces the plate. Thus he has a "southpaw."
spike: A runner can "spike" an infielder by sliding into him and causing an injury with the spikes of his shoes.
spitter: A spitball pitch in which the ball has been altered by the application of spit, petroleum jelly, or some other foreign substance.
squeeze play: A tactic used to attempt to score a runner from third on a bunt. There are two types of squeeze plays: suicide squeeze and safety squeeze.
starter or starting pitcher: The first pitcher in the game for each team.
station-to-station: Oddly enough, this term can mean completely different things. It can be referred to as a close relative of inside baseball, where hit-and-runs and base-stealing are frequent. It can also mean its exact opposite, where a team takes fewer chances of getting thrown out on the bases by cutting down on steal attempts and taking the extra base on a hit; therefore, the team will maximize the number of runs scored on a homer.
stats: Short for "statistics", the numbers generated by the game: runs, hits, errors, strikeouts, batting average, earned run average, fielding average, etc. Most of the numbers used by players and fans are not true mathematical statistics, but the term is in common usage.
Steal (stolen base): In baseball, a stolen base occurs when a baserunner successfully advances to the next base while the pitcher is delivering the ball to home plate. In baseball statistics, stolen bases are denoted by SB. If the catcher thwarts the stolen base by throwing the runner out, the event is recorded as caught stealing (CS). Also see "Uncontested steal."
sticks: See "bush league".
stopper: This term originally a referred to a team’s best starting pitcher, who would be called upon to stop a losing streak. Now it refers to the a team’s top relief pitcher.
strike: When a batter swings at a pitch, but fails to hit the ball within the baselines or when a batter does not swing and the pitch is thrown within the strike zone, or when the ball is hit foul and the Strike Count is less than 2 (a batter cannot strike out on a Foul Ball, however he can Fly Out)
strike out the side: A pitcher is said to "strike out the side" when he retires all three batters in a half inning by striking them out, not necessarily in a row
strike zone: An imaginary box used to call strikes that lies in the following area: vertically from the knees to the nipple line and horizontally from the left side of the plate to the right side of the plate. When the ball passes through the strike zone and the batter either does not swing or misses when he swings one strike has occurred. Despite this formal rule, umpires differ in the strike zones that they recognize or enforce. Major League Baseball has experimented in the recent years with the QuesTec system, which uses laser light technology to standardize the zone. But balls and strikes are still called by umpires, not machines.
submariner: A pitcher who throws underarm.
suicide squeeze: A squeeze play in which the runner on third breaks for home on the pitch, so that, if the batter does not lay down a bunt, then the runner is an easy out (unless he steals home). Contrast this with the safety squeeze.

T

take sign: A sign given to a batter to not swing, or "take", at the next pitch. Sometimes when a new pitcher or reliever comes in, batters are given a general instruction to take the first pitch. Most often, they are told to take a pitch when the count is 3-0.
tater: A home run.
Texas Leaguer or Texas League single: A weakly hit fly ball that drops in for a single between an infielder and an outfielder. See "Bloop".
three-bagger: a triple
three true outcomes: The three ways a plate appearance can end without fielders coming into play: walks, home runs, and strikeouts. Baseball Prospectus coined the term in homage to Rob Deer, who excelled at producing all three outcomes. Traditionally, players with a high percentage of their plate appearances ending in one of the three true outcomes are underrated, as general managers often overestimate the harm in striking out, and underestimate the value of a walk.
tools of ignorance: a catcher's gear.
Tommy John surgery: A type of elbow surgery for pitchers named after Tommy John, a pitcher and the first professional athlete to successfully undergo the operation.
top of the inning: The first half of an inning, during which the visiting team bats, derived from its position in the line score.
touch all the bases.: hit a home run.
TR: Throws right; used in describing a player's statistics, for example: John Doe (TR, BR, 6', 172 lbs.)
triple: A three-base hit. See "hit" and triple (baseball).
triple play: when three outs are made on one play. This is rare.
turn two: to execute a double play
twin killing: a double play.
two-bagger: a double

U

UA or U.A.: Abbreviation for Union Association, a one-year (1884) major league.
Uncle Charlie: A slang term used to describe a curve ball.
Uncontested steal. See also stolen base and defensive indifference.: If a base runner successfully advances to the next base while the pitcher is delivering the ball to home plate but the catcher does not attempt to throw him out, then the steal may be scored as an "uncontested steal." In the game's statistics, the runner would not be credited with a stolen base.
up and in: Same as high and tight.
upper decker: A home run that lands in the stadium's upper deck of seating.
upstairs: a pitched ball that is high, and usually outside the strike zone
up the middle: On the field very close to second base, used to describe the location of batted balls. Also, in a more general sense, the area of the field on the imaginary line running from home plate through the pitcher's mound, second base, and center field. General managers typically build teams "up the middle"; that is, with strong defense in mind at catcher, second base, shortstop, and center field.
utility player: A player (usually a bench player) who can play several different positions.

V

VORP: Value Over Replacement Player, Keith Woolner's method of evaluating baseball players. VORP ranks players by comparing their run production (for batters) to that of an imaginary "replacement-level" player that teams can acquire for the league-minimum salary.

W

walk-off home run: A game-ending home run by the home team. So called because the losing team (usually the visiting team) then has to walk off the field. The term "walk-off" can also be applied to any situation with two outs or less in the last at-bat of the home team (such as the walk-off single, wild pitch, etc.) where the game ends as the winning run scores. For example, a bases loaded bases on balls in the bottom of the last inning has been considered to be known as "a walk-off walk".
warning track: The dirt and finely-ground gravel (as opposed to grass) area bordering the fence, especially in the outfield. It is intended to help prevent fielders from inadvertently running into the fence. 1950s and 60s broadcaster Bob Wolff used to call it the "cinder path". The first "warning tracks" actually started out as running tracks in Yankee Stadium and Cleveland Stadium. True warning tracks did not become standard until the 1950s, around the time batting helmets came into standard use also.
wave: 1. To swing and miss a pitch, usually with a tentative swing. 2. "Doing the wave" in the stands. 3. When an umpire signals to a runner to take a base on an overthrow into the dug-out or in case of a ground rule double or a balk, he "waves the runner" to the next base. 4. When a third-base coach signals to a runner advancing toward the base to continue toward home plate he is said to "wave the runner home."
Web Gem: an outstanding defensive play. Popularized by Baseball Tonight on ESPN.
wheelhouse: A hitter's power zone. "Clem threw that one right into Ruben's wheelhouse. End of story."
Wheel play: upon a bunt to the left side of the infield, the 3rd baseman runs toward home to field the bunt, and the shortstop runs to third base to cover.
wheels: Legs. A player who runs the bases fast has wheels.
whiff: Another term used to describe a strikeout. The phrase has even been immortalized by ESPN's Dan Patrick, who uses it by saying "The whiff'.
WHIP: Walks Plus Hits Per Innings-A measurement of the Pitcher's ability to keep batters off base. Calculated as (Bases on Balls + Hits allowed)/ (Innings pitched)
Winter leagues: Currently, three minor leagues with seasons that happen during the "off-season" of major league baseball. Mainly in Central and South America. Used to include the Cuban League. Now includes the Arizona Fall League, the Puerto Rican League, and the Venezuelan Winter League.
wood: The baseball bat. See "good wood."
Worm burner: A hard hit ground ball that "burns" the ground.
WW: Scoresheet notation for "wasn't watching", used by non-official scorekeepers when their attention has been distracted from the play on field. Supposedly used frequently by former New York Yankees broadcaster Phil Rizzuto.

X

Y

Yardwork: A player is said to be "doing yardwork" by hitting many home runs or exhibiting power. Compare to "Going yard".
Yardjob: A home run. Compare to "Going yard".

Z

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Sources

Dictionary of Baseball
The New Dickson Baseball Dictionary, by Paul Dickson - contains a very extensive list of Baseball jargon and terms.