- K - a strike out.
- Knuckleball / Knuckler - a pitch thrown with no spin. This pitch is usually very slow and can be difficult to hit.
- Lead Off Batter – the first batter up in an inning
- Left On Base - a runner who is left on base after
- Line Drive - a hit that goes straight off the bat into the outfield
- Lineup – the order of batters
- Major Leagues- the professional teams that play in the MLB
- Minor Leagues - the teams that play in the leagues below the MLB. These are often known as farm teams and are lower ranked.
- No Hitter - a game where the pitcher does not allow the opposing team a hit – They still may walk someone and have a no hitter.
- On Base Percentage - a hitter's walks and hits divided by the number of times they are at bat
- On Deck - the hitter who follows the batter who is currently playing
- Out - when a player on offense is removed from play. This can be due to being tagged, forced, struck, or thrown out while on the diamond.
- Outfielder - a fielder whose position on defense is in the outfield. Left, Right, and Center.
- Outside - a pitch thrown outside of the strike zone on the opposite side of the batter.
- Passed Ball - a pitch that goes past the catcher
- Perfect Game - a game where the pitcher does not allow a single hit or single runner on base the whole game. Slightly better than a no hitter.
- Pick Off - when a pitcher or catcher catches a runner off of a base before they are able to steal or return to the bag they came from
- Pinch Hitter - a hitter who takes the place of another batter.
- Pinch Runner - a runner who takes the place of a baserunner after they have successfully hit
- Pitch - the throw made by a pitcher toward Homeplate
- Pitcher's Mound - the mound in the center of the infield where a pitcher stands
- Plate - the base between the batter’s box
- Play Ball – the umpire will call this to begin a game
- Pop Fly - a fly ball
- RBI (Runs Batted In) - when a batter makes contact with the ball allowing a teammate to score a run. The batter is credited with an RBI for every player who is able to score off of their hit.
- Reliever – a pitcher that enters the game after it has begun. They provide a break to struggling/ tired pichers.
- Rightfield - outfield behind the first base side
- Rookie - a player who is in their first season
- Rubber – found on top of the pitcher’s mound. The pitcher must be touching it throughout every pitch.
- Sacrifice - when a hitter bunts in order to advance a teammate to the next base knowing they will likely be thrown out
- Safe - when a runner reaches base without being out from a tag
- Scoring Position - when a base runner is on second or third base
- Screwball - like a curveball, except the pitch moves in the opposite direction
- Seventh Inning Stretch - between the top and bottom halves of the seventh inning. Ballparks invite fans to stand up and stretch their legs as “Take Me Out to the Ball Game” is played.
- Shutout - when a team does not allow the opposing team to score
- Single - a hit which allows the hitter to reach first base safely
- Slide – a baserunner does this as they approach a bag. Often done to avoid a tag.
- Slider - a pitch that drops away from the hitter suddenly upon approach
- Slump - when a batter or team struggles for multiple games in a row
- Softballs - a softball is similar in shape and utility to a baseball, but is usually 2 to 3 inches larger than a baseball in circumference. Softballs are primarily pitched underhand whereas baseballs are pitched overhand.
- Solo - a homerun with no players on base
- Steal - when a runner attempts to move from one base to the next without being tagged out. This occurs between pitches.
- Strike - a pitch the umpire decides is in the strike zone. The batter must swing at this pitch or it will be called a strike. 3 Strikes = 1 Out
- Strike Zone - the area an umpire uses to call balls and strikes. It sits over Homeplate and resides between the batter’s waist and shoulders.
- Strike Out – when 3 strikes have been called
- Swinging Strike - a strike where the hitter swings and misses on the 3rd strike
- Tag – when a baserunner is touched with the ball or glove of a defensive player while off of a base
- Tagging Up – players must remain on a bag while the ball is in the air. Once the ball is caught the can attempt to advance to the next base.
- Top Half of the Inning - the second half of an inning where the home team hits
- Triple - a hit where the batter reaches third base safely
- Turf Shoes - also called turf cleats, are shoes used in baseball and softball that use rubber nubs and treads similar to sneakers but designed for better traction on turf.
- Walk - when a hitter goes to first base after 4 balls have been called by the umpire
- Walk Off - when the home team scores the winning run in the last inning. There is no chance for the opposing team to continue play.
- Warning Track - the track in front of the outfield wall that tells players they are close to the fence
- Wind Up - the motion a pitcher takes when throwing a pitch
