Adaptability

The ability to change attitudes and behaviours to fit changed or changing circumstances.

For me, this differs from flexibility in that adaptation has a semi-permanent quality. In other words, where flexibility is a temporary bend that bounces back to normal, adaptability is the ability to mold oneself into a new form that sticks until the next change of circumstances.

A spring will bend but bounce back (flexibility), but a metal coat-hangar will hold its new shape.