An outswinger is a type of delivery in the sport of cricket. It is bowled by swing bowlers.
An outswinger is bowled by holding the cricket ball with the seam vertical and the first two fingers running along either side of the seam. Once the ball has worn and been polished so that one side is rougher than the other, the rough side is placed on the left (as seen from the bowler's viewpoint). When the bowler delivers the ball, he angles the seam so that it points slightly to the left as well, and releases the ball rotating about a horizontal axis with the seam along the rotational "equator". The angle of the seam to the direction of motion produces an aerofoil effect as the ball moves through the air, pushing it to the left. This is enhanced by differential air pressure caused by movement of air over the rough and smooth surfaces, which also tends to push the ball to the left. The result is that the ball curves, or swings to the left.
From a right-handed batsman's point of view, the swing is away from his body towards the right, i.e. towards the off side. This swing away from the body is the source of the name outswinger. To a left-handed batsman, the swing is in towards the body and towards the leg side.
Outswingers are considered to be one of the more difficult fast deliveries for a right-handed batsman to play. This is because the ball moves away from his body. This means that any miscalculation can result in an outside edge off the bat and a catch going to the wicket-keeper or slips fielders. Also, outswingers often mean the batsman has to swing his bat away from his body, so an inside edge can ricochet on to the wicket and get him out bowled.
To a right-handed batsman, a fast bowler will generally concentrate on bowling repeated outswingers, aiming to tempt the batsman to play away from his body and get him out in one of the ways described above. Occasionally the bowler may try a variation, but switching to a sudden inswinger is difficult because of the fine adjustments that need to be made to ensure it is accurate. More commonly, variation is in the length of the ball, with yorkers and bouncers.
A left-handed batsman has less difficulty facing outswingers, because the ball moves in towards his body (It is a wide if the outswinger doesn't swing into the a left handed batsmen), meaning the batsman's legs are usually in the path of the ball if it misses the bat or takes an edge. This makes it difficult for the bowler to get the batsman out caught, but it does mean there is a chance of bowled or leg before wicket, assuming the ball has not swung enough to miss the leg stump.