1. 第五
The fifth item in a series is the one that you count as number five.
e.g. Joe has recently returned from his fifth trip to Australia.
乔最近结束了第五次澳大利亚之行归来。
2. 五分之一
A fifth is one of five equal parts of something.
e.g. India spends over a fifth of its budget on defence.
印度的国防开支占了其财政预算的 1/5 强。
数词第五
名词五分之一; 第五音,五度音程; <美>五分之一加仑(瓶)