split second

split-second的词性：
n.（名词）

1. An instant; a flash.
一刻；一闪

split-second的词源：

2. Short for split second hands [a stopwatch with two second hands, one beneath the other, one of which may be stopped independently of the other]
split second hands的简写 [有两秒针的跑表，一个在另一个下面，其中之一可以独立于另一个针而停止]