Regain means to get back or recover something that was lost.
The word "regain" is often used when people are talking about getting their time, energy, or physical condition back. For example, if someone has been sick for a long time and they're finally feeling better, we might say "They've regained their health." A sports team that's been losing games might try to regain their winning streak. Even something as simple as a lost book can be regained when you find it again in a messy room. The idea of regaining is about getting back to where you were before, whether that's feeling well or having possession of something important.
To get back; to recover possession of.
