Balk -Any pitching motion that is against the baseball rules. The pitcher is not to try and trick the base runners with illegal motions.
Battery - The battery includes two baseball players, the pitcher and the catcher.
Bunt - When a batter holds the baseball bat out and tries to barely tap the ball vs. taking a full swing at the ball. The batter might do this to advance another base runner.
Change up - A slow pitch that is meant to look much faster.
Cleanup - The fourth batter in the batting order. Usually a power hitter.
Count - The number of balls and strikes on a batter. For example a 3/2 count means there are three balls and two strikes on the batter.
Diamond -The four bases of the baseball infield.
Double play - A defensive baseball play that results in two outs.
Error - A mistake in fielding the baseball by the defense that allows a batter to reach base or a base runner to advance.
Fly ball - A baseball that is hit high into the air.
Foul ball -A baseball that is hit outside the field of fair play.
Full count - When the pitch count has 3 balls and 2 strikes. The next strike or ball will end the at bat. If the batter hits the baseball foul, then the count remains 3 and 2.
Ground ball - A baseball that is hit on the ground. Also called a "grounder".
Hit and run - A baseball play where the base runner begins to run when the pitch is released. It's the batter's responsibility to hit the baseball into play so the runner will not get out. This gives the base runner a head start.
Hit for the cycle - When a baseball player hits a single, a double, a triple, and a home run in one game.
Lead Runner - The first base runner when more than one runner is on base.
Load the bases - When a base runner is at all three bases.
On-deck - The next batter due to bat.
Pinch hitter - A substitute baseball hitter.
Pinch runner - A substitute base runner.
Pitch around - When the pitcher does not throw the batter a pitch near the plate in order to walk the batter.
Pitch out - A pitch that cannot be hit by the batter. Used to walk a batter on purpose or to try and catch a base stealer.
Position player - Any baseball player but the pitcher.
Power hitter - A strong batter that hits the baseball far, often for home runs or extra bases.
Relay - When one fielder throws the baseball to another fielder who then throws the baseball to another fielder.
Reliever or relief pitcher - A replacement pitcher. Usually comes in the game when the starting pitcher grows tired.
Runners at the corners - Base runners on 1st and 3rd.
Scoring position - A base runner on 2nd or 3rd base is in scoring position.
Strike zone - The area above home plate where strikes are called. The pitch must be over home plate, above the batter's knees, and below the batter's belt.
Walk - When the pitcher throws four balls to a batter, the batter gets to go to first base automatically.