Baseball Glossary

batting average

Also: BA, AVG, average

A statistic that measures how often a batter gets a hit. Calculated by dividing hits by at-bats. A .300 average (3 hits every 10 at-bats) is considered very good.

RBI

Also: run batted in, runs batted in, ribbie, ribbies

A run batted in — credited to a batter when their at-bat results in a run scoring (except on errors or double plays). Hitting a sacrifice fly that scores a runner counts as an RBI.

on-base percentage

Also: OBP, on base percentage, on base pct

A statistic measuring how often a batter reaches base. Includes hits, walks, and hit-by-pitches. Higher than batting average because it counts walks. A .400 OBP is excellent.

slugging percentage

Also: SLG, slugging, slugging pct

A statistic measuring the power of a hitter. Calculated by total bases divided by at-bats. A single = 1, double = 2, triple = 3, home run = 4. Higher slugging means more extra-base hits.

on-deck

Also: on deck, on-deck circle, on deck circle

The batter who is next up to hit. They wait in the on-deck circle (a marked area near the dugout) taking practice swings and timing the pitcher. Being "on deck" means you're one batter away from hitting.

cleanup hitter

Also: cleanup, cleanup spot, 4-hole, four hole

The 4th batter in the lineup, typically the team's best power hitter. Called "cleanup" because ideally the first three batters get on base and the 4th batter "cleans up" by driving them in.

lead-off hitter

Also: leadoff, leadoff hitter, lead off hitter, 1-hole

The first batter in the lineup. Usually the team's fastest player with a high on-base percentage. Their job is to get on base and set the table for the hitters behind them.

switch hitter

Also: switch hitting, switch hits

A batter who can hit from both sides of the plate — left-handed and right-handed. Switch hitters bat from the opposite side of the pitcher (right-handed vs. a lefty pitcher, left-handed vs. a righty) to gain an advantage seeing the ball.

designated hitter

Also: DH

A player who bats in place of the pitcher but does not play a defensive position. The DH rule allows teams to keep a strong hitter in the lineup without requiring the pitcher to bat.

bunt

Also: bunts, bunting, bunted

A batting technique where the hitter holds the bat still and lets the ball hit it softly, placing it in the infield. Used for sacrifice bunts (advance runners), bunt-for-hits (beat out a throw), or squeeze plays (score a runner from 3rd).

sacrifice fly

Also: sac fly

A fly ball caught by an outfielder that allows a runner on 3rd to tag up and score. The batter is out, but the run scores. It doesn't count as an at-bat for the hitter.

sacrifice bunt

Also: sac bunt, sacrifice

A bunt where the batter intentionally gives themselves up (gets out) to advance a runner into scoring position. The batter squares around and softly bunts the ball, forcing the defense to field it while the runner advances.

double play

Also: double plays, twin killing, DP

A defensive play where two outs are recorded on a single batted ball. The most common is the 6-4-3 (shortstop to 2nd baseman to 1st baseman) on a ground ball with a runner on 1st.

force out

Also: force, force play, force at

When a baserunner is forced to advance because the batter becomes a runner, the defense can get an out by touching the base the runner is forced to, rather than tagging the runner. Removes the need for a tag play.

rundown

Also: rundowns, pickle

When a baserunner is caught between two bases and the defense throws the ball back and forth to tag them out. The goal for the defense is to use as few throws as possible — each throw is a chance for an error.

cutoff man

Also: cutoff, relay man

An infielder who positions themselves between an outfielder and the target base to receive and redirect throws. The cutoff man can let the throw go through, cut it off and throw to another base, or hold the ball. Proper cutoff alignment is critical for preventing extra bases.

relay

Also: relay throw, relay man

A throw from an outfielder to an infielder (the relay man) who then throws to the target base. Used on deep hits where a direct throw would be too far. The relay man lines up between the outfielder and the base to keep the throw accurate.

backup

Also: backing up, back up

Positioning yourself behind a teammate who is receiving a throw in case the ball gets past them. Every throw should have a backup — for example, the pitcher backs up home plate on throws from the outfield, and outfielders back up each other on fly balls.

shift

Also: defensive shift, infield shift

When the defense repositions fielders away from their normal spots based on where the batter is likely to hit the ball. For example, against a strong pull hitter, infielders may all shift to one side of the diamond.

charge the ball

Also: charging, charge it, charge

Running toward a ground ball instead of waiting for it to come to you. Charging cuts down the time the batter has to reach base and shows aggressiveness. Fielders must stay low and field the ball cleanly while moving forward.

bare hand play

Also: bare hand, bare-hand, barehanded

Fielding a slowly hit ball with the bare (non-glove) hand and throwing in one motion. Used on slow rollers or bunts when there isn't time to field with the glove, transfer the ball, and throw. Requires good hands and accuracy.

pop fly

Also: pop up, pop-up, popup

A high, short fly ball hit to the infield. Pop flies are usually easy outs. The infield fly rule may apply with runners on base to prevent the defense from intentionally dropping it.

can of corn

Also: routine fly ball

A high, easy fly ball hit directly to an outfielder. The term comes from old-time grocery stores where clerks would knock cans off high shelves and catch them easily. Considered the easiest play in baseball.

infield fly

Also: infield fly rule

With runners on 1st and 2nd (or bases loaded) and less than 2 outs, a fair fly ball that an infielder can catch with ordinary effort results in the batter being automatically out. This rule prevents the defense from intentionally dropping the ball to get a double or triple play.

fastball

Also: heater, heat, gas, four-seam, two-seam

The fastest and most basic pitch in baseball. Thrown with maximum velocity in a straight line. A four-seam fastball is the straightest and fastest; a two-seam fastball has slight movement. Usually the first pitch young players learn.

changeup

Also: change-up, change up, change

An off-speed pitch designed to look like a fastball but arrive 8-15 mph slower. The arm motion is the same as a fastball, but the grip slows the ball down. Effective because it disrupts the batter's timing.

curveball

Also: curve, hook, deuce, Uncle Charlie, yakker

A pitch that breaks downward (and sometimes sideways) as it approaches the plate. Thrown with topspin by snapping the wrist. Looks like it's coming in high but drops through the zone. Not recommended for very young arms.

slider

Also: slide piece

A pitch that looks like a fastball but breaks sharply to the side as it reaches the plate. Faster than a curveball but with less vertical drop. The tight spin creates late horizontal movement that can fool batters.

strikeout

Also: K, strike out, punch out, whiff

When a batter accumulates three strikes and is called out. A "K" in the scorebook means a strikeout looking (called third strike); a backwards "K" means a strikeout swinging. Strikeouts are the most dominant way for a pitcher to get outs.

walk

Also: base on balls, BB, free pass

When a batter receives four pitches outside the strike zone (balls) during an at-bat, they are awarded first base. Also called a "base on balls." A walk counts toward on-base percentage but not batting average.

full count

Also: 3-2 count, three-two count, full

A count of 3 balls and 2 strikes. The next pitch will either result in a walk (ball 4), strikeout (strike 3), or be put in play. Runners often go on the pitch in a full count because they'll advance on a walk anyway.

hit by pitch

Also: HBP, hit batter, plunked, beaned

When a pitched ball hits the batter, the batter is awarded first base. The batter must make an effort to avoid the pitch. Hit by pitches count toward on-base percentage. Getting hit often can be painful but is part of the game.

mound visit

Also: visit to the mound

When a coach or catcher goes to the pitcher's mound to talk to the pitcher. Used to calm a struggling pitcher, discuss strategy, or give a reliever time to warm up. Teams are limited in the number of mound visits per game.

wild pitch

Also: wild pitches, WP

A pitch so far outside the strike zone that the catcher cannot catch or block it, allowing baserunners to advance. Scored as the pitcher's fault (unlike a passed ball, which is the catcher's fault).

passed ball

Also: passed balls, PB

A pitch that the catcher should have caught or blocked but didn't, allowing runners to advance. Unlike a wild pitch, a passed ball is scored as the catcher's error.

ERA

Also: earned run average

Earned Run Average — the average number of earned runs a pitcher gives up per 9 innings. Calculated as (earned runs × 9) ÷ innings pitched. A lower ERA is better. Under 3.00 is excellent; under 4.00 is good.

ground ball

Also: ground balls, grounder, groundout

A batted ball that rolls or bounces along the ground in the infield. Fielders must field it cleanly and throw to a base for the out. Ground balls with runners on base often lead to force plays or double plays.

fly ball

Also: fly balls, fly out, flyout

A batted ball hit high into the air. If caught by a fielder before it touches the ground, the batter is out. Runners on base can tag up and advance after the catch.

line drive

Also: line drives, liner, rope, frozen rope

A batted ball hit hard and on a relatively straight trajectory. Line drives are dangerous for baserunners because they can be caught quickly, leading to easy double plays if runners are off their bases.

tag up

Also: tags up, tagging up, tag

After a fly ball is caught, a baserunner must touch (or "retouch") their current base before advancing. The runner waits on the base, watches for the catch, then runs to the next base. If they leave early and the defense appeals, the runner is out.

go halfway

Also: halfway, goes halfway

A baserunning strategy on fly balls where the runner advances to a point roughly halfway between their current base and the next one. If the ball drops, they can easily advance. If caught, they can retreat safely. Used on medium-depth fly balls where tagging up isn't ideal.

on contact

Also: going on contact

A baserunning strategy where the runner takes off running as soon as the ball is hit (on contact with the bat), regardless of where it goes. Used on ground balls to avoid double plays and with 2 outs when you run on anything.

lead off

Also: lead, leads, taking a lead, primary lead, secondary lead

The distance a baserunner takes away from their base before the pitch is thrown (primary lead) or as the pitch is delivered (secondary lead). A bigger lead gives a head start for stealing or advancing, but increases the risk of being picked off.

steal

Also: stolen base, stealing, SB

When a baserunner advances to the next base during the pitch without the ball being hit. Requires speed and a good jump (timing). The runner takes off as the pitcher delivers and tries to beat the catcher's throw to the base.

delayed steal

Also: delayed steals

A steal where the runner doesn't break for the next base right away. Instead, they wait until the catcher throws the ball back to the pitcher (or until the middle infielders relax), then take off. Works by catching the defense off guard rather than relying on pure speed.

hit and run

Also: hit-and-run

An offensive play where the baserunner starts running with the pitch and the batter is required to swing, no matter what. The runner gets a head start, and the batter tries to hit the ball behind the runner or through the hole left by the fielder covering the base.

squeeze play

Also: squeeze, squeeze bunt

A play designed to score a runner from 3rd base using a bunt. The batter bunts the ball while the runner breaks for home. There are two types: the suicide squeeze (runner goes on the pitch) and the safety squeeze (runner waits to see if the bunt is down).

suicide squeeze

Also: suicide

A squeeze play where the runner on 3rd breaks for home as soon as the pitcher begins the delivery — before the batter bunts. High risk, high reward: if the batter misses the bunt, the runner is almost certainly out at home.

safety squeeze

A squeeze play where the runner on 3rd waits to see if the batter successfully bunts the ball before breaking for home. Safer than the suicide squeeze because the runner isn't committed, but the batter needs to place the bunt well to give the runner time to score.

rally

Also: rallies, rallying, comeback

When a team strings together multiple hits, walks, or runs in a single inning to come back or build a big lead. A rally cap (wearing your hat inside out) is a fun superstition to spark a comeback.

shutout

Also: shut out, blanked

When a team (or pitcher) holds the opponent to zero runs for the entire game. A combined shutout involves multiple pitchers. Throwing a shutout is one of the most dominant pitching performances.

no-hitter

Also: no hitter, no-no

A game in which a pitcher (or pitching staff) does not allow any hits for the entire game. The opponent can still reach base via walks, errors, or hit-by-pitches, but no hits. Rarer and more impressive than a shutout.

grand slam

Also: grand salami, granny

A home run hit with the bases loaded (runners on 1st, 2nd, and 3rd), scoring 4 runs on one swing. The most runs that can score on a single play. One of the most exciting moments in baseball.

walk-off

Also: walk off, walkoff, walk-off hit, walk-off homer

A hit or play in the bottom of the last inning that gives the home team the winning run, ending the game immediately. Called a "walk-off" because the losing team walks off the field. One of the most thrilling endings in baseball.

extra innings

Also: extras, free baseball

Innings played beyond the standard game length (6 innings in youth, 7 in high school, 9 in pro) when the score is tied. The game continues until one team leads at the end of a complete inning. Some youth leagues use special rules or a mercy rule instead.

mercy rule

Also: run rule, slaughter rule, run ahead rule

A rule in youth and amateur baseball that ends the game early if one team is ahead by a large margin (commonly 10+ runs after a certain number of innings). Designed to prevent blowouts and save players from unnecessary innings. Rules vary by league.