v.1. To abandon one's way, course, or direction and return: The road became too muddy, and we had to turn back. Once you sign the contract, you cannot turn back.
2. To force someone or something to stop and go back: Our surprise attack turned back the advancing army. The police turned us back at the border because we forgot our passports.
3. To fold something down: Turn back the page's corner to save your place in the book. The tailor turned the edge of the fabric back and made a hem.