1ORD 第一千 The thousandth item in a series is the one that you count as number one thousand. 第一千 [emphasis]
The magazine has just published its six thousandth edition.
这本杂志刚刚出版了第 6,000 期。
If you say that something has happened for the thousandth time, you are emphasizing that it has happened again and that it has already happened a great many times.第一千(强调某事发生次数之多)
The phone rings for the thousandth time.
电话都响了一千次了。
2FRACTION 千分之一 A thousandth is one of a thousand equal parts of something. 千分之一
...a dust particle weighing only a thousandth of a gram.