Screwball
A screwball is a baseball pitch that is thrown so as to break in the opposite direction of a curveball. Thrown by a right-handed pitcher, a screwball breaks from left to right from the point of view of the pitcher. The pitch therefore moves in on a right-handed batter and away from a left-handed batter. Thrown by a left-handed pitcher, a screwball breaks from from right to left, moving in on a left-handed batter and away from a right-handed batter.
Screwballs are difficult to throw due to an awkward hand motion, and are therefore rare. Skill at throwing screwballs is highly prized, partly because it is rare and therefore unexpected, and partly because a ball curving towards the left of the plate is more likely to be hit to the left where there are more players to field it.
See also
