noun
trading stamp
A stamp given by retailers to customers as a loyalty reward, which can be collected and exchanged for goods or discounts. Common in Japanese point-card systems.
このスーパーでは、買い物のたびにトレーディングスタンプがもらえる。
At this supermarket, you get trading stamps every time you shop.
貯めたトレーディングスタンプを景品と交換した。
I exchanged the trading stamps I had collected for a prize.