rebound 回弹、回升
rebound guy/girl 备胎，本质就是temporary lover，临时情人
rebound relationship 分手后疗伤期随随便便谈的恋爱
例句：
I don't really like her, she's just my rebound girl, this reboundrelationship doesn't count.
我其实不喜欢她啦，她就是个备胎而已，这段感情不算数。
虽然rebound guy/girl这个词很实用，但是这样没人性的话大家还是要少说。