Tweener (of English. Between, "between" ) is an informal term for players in basketball. Just like the Swingman and the Combo Guards they can be assigned to any exact position.
We distinguish between two types of Tweenern.
In the first case, they can use the body size of a "larger" (PG 1, SG 2, SF 3, ...) have position. For example, so a small forward with the size of a Power forwards ( by NBA scale from 206 cm). You can play these two positions, which makes them highly versatile.
In the second case, there are, for example, Shooting Guards with the size of point guards (usually under 191 cm), or a power forward with the size of a small Small Forwards ( about 198 cm), so players who simply are too small for their respective positions. These players have it most difficult to establish themselves in the NBA, as prototypical body sizes are preferred. In European basketball or outside of the NBA such players, however, are often to be found.