1.Lit. [for something] to rebound; [for something] to return bouncing from where it had been. The ball bounced back from the wall.A rubber ball always bounces back.
2. and bounce back (after something) Fig. [for someone] to recover after a disability, illness, blow, or defeat. (See also rebound from something.) She bounced back from her illness quickly.She bounced back quickly after her illness.
Recover quickly, as in She had pneumonia, but she bounced back in less than a week. This expression is a metaphor for the rebound of a ball or some elastic material.