nanosecond
/ˈnænəʊˌsekənd/(缩略词：ns)
noun
1- one thousand millionth of a second纳秒。
1.1
- informal a very short time; a moment〈非正式〉很短的时间; 一瞬间：
she can flick between manic laughter and tears in a nanosecond.
她可以在一阵狂笑之后顷刻间变得眼泪汪汪。