- 1: to draw out and twist fiber into yarn or thread
- 2: to form a thread by extruding a viscous rapidly hardening fluid —used especially of a spider or insect
- 3a : to revolve rapidly : gyrate
- b : to feel as if in a whirl : reel <my head is spinning>
- 4: to move swiftly especially on or as if on wheels or in a vehicle
- 5: to fish with spinning bait : troll
- 6a of an airplane : to fall in a spin
- b : to plunge helplessly and out of control
The main aim of spin bowling is to bowl the cricket ball with rapid rotation so that when it bounces on the pitch it will deviate from its normal straight path, thus making it difficult for the batsman to hit the ball cleanly. The speed the ball travels is not critical, and is significantly slower than that for fast bowling. A typical spin delivery has a speed in the range 70–90 km/h (45–55 mph).
Spin bowling is divided into four different categories, depending on the particular physical technique used. There is virtually no overlap between the two basic biomechanical techniques of wrist spin and finger spin.
- Leg spin - Right-handed with wrist spin technique. (e.g. Shane Warne)
- Left-arm orthodox spin - Left-handed with finger spin technique. (e.g. Monty Panesar)
- Left-arm unorthodox spin - Left-handed with wrist spin technique. (e.g. Brad Hogg)
- Off spin - Right-handed with finger spin technique. (e.g. Muttiah Muralidaran)
Depending on technique, a spin bowler uses either predominant wrist or finger motion to impart spin to the ball around a horizontal axis that is at an oblique angle to the length of the pitch. This sort of spin means it is also possible for the Magnus effect to cause the ball to deviate sideways through the air, before it bounces. Such deviation is called drift. The combination of drift and spin can make the ball's trajectory complex, with a change of direction at the bounce.
This variety of trajectories achievable by a spin bowler can bewilder inexperienced or poor batsmen.
Spin bowlers are generally given the task of bowling with an old, worn cricket ball. A new cricket ball better suits the techniques of fast bowling than spin bowling, while a worn one grips the pitch better and achieves greater spin. Spin bowlers are also more effective later in a game, as the pitch dries up and begins to crack and crumble. This again provides more purchase for the spinning ball and produces greater deviation.