Rakeback
Rakeback originated in online poker, where the "rake" is the small percentage the poker room takes from each pot. Rakeback gives you a portion of that fee back. The concept has expanded to casino gaming, where "rakeback" or "wager-based cashback" means the casino returns a percentage of the total amount you've wagered (or the theoretical house edge applied to your wagers, known as the house edge times your wager volume).
This is different from standard loss-based cashback. Regular cashback refunds a percentage of your net losses. Rakeback refunds a percentage based on how much you've bet, regardless of whether you won or lost. You could have a winning session and still receive rakeback. That makes it particularly attractive for high-volume players.
Crypto casinos have popularised instant rakeback as a VIP feature. Stake.com, for example, calculates rakeback in real time and credits it to your account as you play. The percentages are typically small (0.5% to 1% of total wager) but for high-volume players betting millions per month, those fractions add up to significant money.