1. to bend (a thing), forming an elbow-shape (transitive)

2. to change the state or direction of (a thing) by inclining, curving, or crossing (transitive)

3. to change the orientation or outcome of (a thing, a course of events) (transitive, figuratively)

4. to change direction; to curve (reflexive)

5. (of a ray of light) To change direction, to bend, as at the interface between two media (reflexive)

6. to change in tone or pitch (reflexive, music)