1. To return something to its original location. A noun or pronoun can be used between "cast" and "back." If you decide against any of those library books, please cast them back where you found them.

2. To refer or think back to something. A noun or pronoun can be used between "cast" and "back." In the second chapter of your thesis, be sure to cast back to the topics and themes you presented in chapter one. I tried casting my mind back to high school algebra and couldn't remember a thing.