瞬间用英语可以说成 "instant" 或 "moment". 来源是拉丁语 "instans"，意思是“立刻”。

例句：

The instant he saw the fire, he called the fire department. (他一看到火，就报了消防队。)

In an instant, the situation changed. (一瞬间，局面就变了。)

Time seems to stop in the instant before a disaster. (在灾难发生前的那一刻，时间似乎静止了。)