A variation delivery for an off spin bowler, Saqlain Mushtaq has been credited with creating it. Teesra comes from the Urdu meaning "the third one".
A doosra with extra bounce.
A ball that drifts in from wide of off stump and turns away from the right hander sharply with extra bounce.
A finger spinner's back-spinner. Similar to a wrist spinner's slider or flipper.
The actual definition of this ball has yet to have been definitively announced.