This is an alphabetical list of selected unofficial and specialized terms, phrases, and other jargon used in baseball, along with their definitions, including illustrative examples for many entries.
0–9 0
"Oh and ..." See count.
1 The number 1 in baseball refers to the pitcher's position, a shorthand call for throwing to first, a single hit, and a fastball sign.
1-2-3 inning
An inning in which a pitcher faces only three batters and none safely reaches a base. "Three up, three down."
1-2-3 double play
A double play in which the pitcher (1) fields a batted ball and throws home to the catcher (2), who retires a runner advancing from third. The catcher then throws to the first baseman (3) to force out the batter. These almost always happen with the bases loaded.
1-6-3 double play
The pitcher (1) fields a batted ball and throws to the shortstop (6) to force out a runner advancing to second. The shortstop then throws to the first baseman (3) to force out the batter.
2 Catcher (2) gets a "Two!" call for throws to second, a "two-bagger" is a double, and the number 2 signs for a curveball.
2–2–2 (2 balls, 2 strikes, 2 outs)
See deuces wild.
20–80 scale
MLB scouts use a 20-80 scale to grade players: 50 is average (MLB level), with 20 being very low and 80 elite. Applies to overall ability & specific skills like hitting or pitching speed.
3 The first baseman (3) receives throws with shouts of "Three!", nabs runners attempting triples ("three-baggers"), and the number 3 might signal a slider from the pitcher.
3-2-3 double play
The first baseman (3) fields a batted ball and throws to the catcher (2), who retires a runner advancing from third and then throws back to the first baseman to force out the batter. These almost always happen with the bases loaded.
3-6 double play
The first baseman (3) fields a batted ball, steps on first (to force the batter out), and then throws to the shortstop (6), who tags out a runner. Another possibility is a line drive caught by the first baseman, who throws to the shortstop, who then steps on second base for a second out.
3-6-1 double play
The first baseman (3) fields a batted ball and throws to the shortstop (6) to force out a runner at second. The shortstop then throws to the pitcher (1) (who is now covering first because the first baseman was busy fielding the ball) to force out the batter.
3-4-3 double play
The first baseman (3) fields a batted ball and throws to the second baseman (4) to force out a runner at second. The second baseman then throws back to the first baseman to force out the batter.
3-6-3 double play
The first baseman (3) fields a batted ball and throws to the shortstop (6) to force out a runner at second. The shortstop then throws back to the first baseman to force out the batter.
4
The second baseman, in scorekeeping shorthand. A shout of "Four!" indicates the ball should be thrown to home plate. A "four-bagger" is a home run. In the context of pitching, the number4 is a common sign (and nickname) for a change-up.
4-6-3 double play
The second baseman (4) fields a batted ball and throws to the shortstop (6), who forces out a runner at second and then throws to the first baseman (3) to force out the batter.
45-foot line
The 45-foot line in baseball marks the area a batter-runner must stay in to avoid being called out for interfering when running to first base.
45-degree line
An informal term referring to a hypothetical line drawn at a 45 degree angle from the front plane of the #rubber to the first base line. It can be used as a reference point to determine whether a left handed pitcher legally stepped at first base while attempting a pickoff. A pitcher is required to step to the base to which he is throwing, and failing to do so is a balk.
4 wide ones
Four consecutive pitches deliberately wide of the strike zone. Preacher Roe summarized this strategy to Stan Musial as "I throw him four wide ones and try to pick him off at first."
5
The third baseman, in scorekeeping shorthand.
5 hole
Between a player's legs (the catcher's in particular). From the hockey term for how a puck is advanced past the goalie ("through the five hole").
5.5 hole
The space between the third baseman (5) and shortstop (6).
Made famous by perennial batting champion Tony Gwynn of the San Diego Padres as his description of where he liked to hit the baseball.
5-4-3 double play
The third baseman (5) fields a batted ball and throws to the second baseman (4) to force out a runner advancing from first. The second baseman then throws to the first baseman (3) to force out the batter.
5-4-3 triple play
3rd baseman (5) fields a hard-hit ball and steps on third for a force out on R2 (6), then throws a laser to 2nd Baseman (4) to force out R1 (7) at second. Finally, 2nd Baseman (4) fires the ball to 1st Baseman (3) to complete the triple play by retiring the batter (2).
5-tool player
A position player (non-pitcher) like Willie Mays, Mickey Mantle, Andre Dawson, Duke Snider, Vladimir Guerrero, and Ken Griffey Jr., who excels at: hitting for average hitting for power base running throwing fielding
6
The shortstop, in scorekeeping shorthand.
6-4-3 double play
The shortstop (6) fields a batted ball and throws to the second baseman (4), who forces out a runner advancing from first and then throws to the first baseman (3) to force out the batter.
7
The leftfielder, in scorekeeping shorthand.
7-2, 8-2, or 9-2 double play
A fly ball is caught by an outfielder, and a runner tries to tag up and score from third but is tagged out by the catcher.
8
The centerfielder, in scorekeeping shorthand.
9
The rightfielder, in scorekeeping shorthand.
9 to 0
The official score of a forfeited game in Major League Baseball.
12–6 curveball
A type of curveball, the motion of which evokes the hands of a clock.
30-30 club
Players who hit 30 home runs and steal 30 bases in a single season.
40-40 club
Players who hit 40 home runs and steal 40 bases in a single season.
50-50 club
Players who hit 50 home runs and steal 50 bases in a single season.
55-footer
A pejorative term for a pitch that bounces short of the feet between the pitching rubber and the plate.
90 feet
When a runner advances one base, he "moves up 90 feet"—the distance between successive bases. A runner on third base is "90 feet away" from scoring.
A A-Ball or Class A As of the 2022 season, "Class A" is the lowest grouping of modern affiliated minor league baseball, with sub-categories of "High-A" and "Single-A". "Short-Season A" leagues also existed before 2021. High-A is divided into three leagues: Midwest League, Northwest League, and South Atlantic League. Single-A is also divided into three leagues: California League, Carolina League, and Florida State League.
AA "Double-A" (AA) is the second-highest level of minor league baseball (below AAA), and as of 2022 includes the Eastern League, the Southern League, and the Texas League. "AA" is also the abbreviation for the American Association, which has been the name of numerous professional baseball leagues: a short-lived major league of the 19th century, a minor league for much of the 20th century, and an independent minor league that became a "Partner League" of Major League Baseball in 2021.
AAA "Triple-A" is the highest level of minor league baseball. As of 2022, this level includes the International League and the Pacific Coast League.
AAAA player "Four-A player" (alternatively, "Quadruple-A player") is a term for a minor-league player who is consistently successful in the high minor leagues (AAA), but cannot translate that into success at the major-league level. Poor management can be responsible. "AAAA" may also informally refer to high-quality but unaffiliated foreign baseball leagues outside North America where play is considered less competitive than in MLB but more competitive than in AAA; this is usually restricted to describing Japan's NPB.
aboard When a runner is on base. When there are runners safely on base, there are "runners aboard".
ace The best starting pitcher on the team, who is usually first on a pitching rotation.
advance a runner To move a runner ahead safely to another base, often the conscious strategy of a team that plays small ball. If a batter does make an out, his plate appearance will have been less negative if he still got a runner into scoring position; in certain situations, batters even deliberately sacrifice themselves.
ahead in the count A term that signifies whether the batter or pitcher possesses the advantage in an at-bat. If a pitcher has thrown more strikes than balls to a batter in an at-bat, the pitcher is ahead in the count; conversely, if the pitcher has thrown more balls than strikes, the batter is ahead. If the pitcher is ahead in the count, the batter is in increasing danger of striking out. If the batter is ahead, the pitcher is in increasing danger of walking him.
aim the ball Sometimes when a pitcher tries a bit too carefully to control the location of a pitch, he is said to "aim the ball" instead of throwing it. This is a different meaning of "aim" from the situation in which a pitcher aims a pitch at a batter in an effort to hit him.
airmail
Slang for a fielder's errant throw that sails high over the player to whom he intended to throw the ball. For example, if the third baseman were to throw the ball over the first baseman's head and into the stands, he is said to have "airmailed" the throw. "But Chandler airmailed her throw to third into the dugout..."
alabaster blast Coined by Pittsburgh Pirates announcer Bob Prince, this was a hit made sharply downward in the infield, like a Baltimore chop, that would bounce higher than normal due to the extraordinarily hard dirt at Forbes Field, allowing the batter time to safely reach first base.
alley Also "gap" or "power alley", the space between the leftfielder and the centerfielder, or the rightfielder and centerfielder. If a batter hits the ball "up the alley" with enough force, he has a stronger chance of advancing beyond first base and being credited with an extra-base hit. Typically, this is an appropriate term for describing a line drive or ground ball; fly balls that hit the wall are not normally described this way.
ambush Swinging at (and especially hitting) the first pitch.
American League (AL)
The junior of the two existing Major Leagues.
American League Championship Series (ALCS)
The season's final best-of-seven playoff series which determines the American League team that will advance to the World Series. The ALCS–like its analog, the NLCS–came into being in 1969. The ALCS winner takes the American League pennant and the title of American League Champion for that season. The winners of the American League Division Series have met in the ALCS since 1995.
American League Division Series (ALDS)
The second round of the league playoffs. The top two division winners and the winners of the two Wild Card series are paired off in two best-of-five series, the winners of which advance to the ALCS.
Annie Oakley A free ticket to attendance at a ballgame or to first base (a "free pass" or "base on balls").
appeal play
A play in which the defense has an opportunity to gain a favorable ruling from an umpire by addressing a mistake by the offense or seeking the input of another umpire. Appeals require the defense to make a verbal appeal to an appropriate umpire, or if the situation being appealed is obvious a player may indicate an appeal with a gesture. The onus is on the defense to make an appeal; umpires will not announce potential appeal situations such as runners failing to touch a base, batting out of order, or unchecked swings until an appeal is made.
Arizona Fall League (AFL)