Usually, the term being used for this is rakeback by casinos. But check the percentage as it varies from one casino to another as well as it depends on how much you wagered on their site. You may be looking forward to this rakeback at the end of your session, but you may get disappointed as most have low percentage vs. your wagered amount. But this feature is already good as compared to none. At least get something from your wagered amount at the end of the session.
I also think this is what they mean by "loss bonus". Rakeback is one of my favorite bonuses. It's always a pleasure to get few bucks which alow you to play more after you have nothing left on your account balance. Besides, it usually doesn't have a wagering requirement.
You shouldn't expect much, though. And I believe it doesn't depend only on how much you have wagered but it depends on the house edge too. The higher the house edge the higher the rakeback you get.