Appeal - The act of a defensive team protesting whether or not the offensive team actions are an infraction of rules of baseball. Usually occurs when the defensive team appeals if the offensive player touched a base or whether the offensive player's swing was a strike.

Around The Horn - A defensive double play that involves the third, second, and first baseman, in that order.

Astro-turf - An artificial surface that is used for covering a baseball field. The surface is utilized in stadiums that are enclosed where no sunlight is available to support the growth of natural grass.

At Bat - An official appearance at the plate. Appearances when a batter is hit by the baseball, walks, sacrifices, or is interfered with does not count as an at bat.

Average - A statistic that reflects a players performance of play. Commonly used averages are batting average, fielding average, earned run average, and slugging percentage.